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The main and segmental bronchi
Anatomy
The main and segmental bronchi
Trachea and main bronchi viewed from the front
Harold Ellis
Trachea Anterior bronchus
Abstract
Apico-posterior bronchus
The trachea bifurcates at the level of T4 in the cadaver; in the living subject it descends to T6 in full inspiration. The right main bronchus is wider, shorter and more vertical than the left; therefore more likely to aspirate a foreign body or to be inadvertently entered by a catheter or endotracheal tube. The lungs are divided into bronchopulmonary segments, each with its own blood supply and bronchial branch. The right lung has an upper, middle and lower lobe, the left an upper and lower lobe, the upper having a lingular segment, somewhat equivalent to the right middle lobe but supplied from the upper lobe bronchus. The upper lobe on each side comprises an apical, anterior and posterior segment, the lower lobe an apical and posterior, lateral and anterior basal segment. The right lower lobe also has a small medial basal (cardiac) segment. The right middle lobe has a medial and lateral segment, while the lingula has a superior and inferior segment. The segmental anatomy of the lungs enables segmental resections to be performed and is important in postural drainage of the lungs.
Carina Right main bronchus Upper lobe bronchus Lower part of right main bronchus Middle lobe bronchus Lower lobe bronchus Medial basal bronchus (cardiac)
Apical bronchus
Keywords anatomy; bronchopulmonary; bronchus; lingula; lobe; lower;
Posterior basal bronchus
middle; postural drainage; right; segmental resection; segments; upper
Anterior basal bronchus Lateral basal bronchus Lingula
The main bronchi In the cadaver, the trachea bifurcates at the level of the 4th thor acic vertebra. In the erect individual, in full inspiration, this level lowers to the 6th thoracic vertebra. The right main bronchus is shorter, wider and more vertical than the left (Figure 1). It is shorter because it gives off its upper lobe bronchus after a course of only 2.5 cm, it is wider because it supplies the bulkier lung, and it is more vertical because the left bronchus has to pass later ally under the aortic arch to reach the left lung. Because of this, an inhaled foreign body, the tip of an aspirating catheter, or the end of an endotracheal tube that is too long for the size of the patient is much more likely to pass into the right, rather than the left, bronchus. The right pulmonary artery lies below, and then passes in front of, the right main bronchus, while the azygos vein arches over it. The left main bronchus is double the length of the right. It passes under the aortic arch, to cross in front of the oesophagus and descending aorta, with the left pulmonary artery first above and then in front of it.
Figure 1
The bronchopulmonary segments The lungs are divided functionally into a series of bronchopulmonary segments (Figures 2 and 3), each with its own bron chus and its own blood supply, and with its parenchyma distinct from its adjacent segments. Radiological diagnosis, surgical seg mental resections and the postural drainage of collapsed lung seg ments depend on this segmental anatomy. The main difference between the two lungs is that the lingular branches arise from the left upper lobe bronchus, whereas the middle lobe branches arise from the lower part of the main bronchus on the right. The right lung: the right main bronchus, after a course of 2.5 cm, gives off the upper lobe bronchus, which trifurcates into the api cal, posterior and anterior segmental bronchi. The main bron chus continues for about 3 cm, then gives off the forward and downwardly directed middle lobe bronchus, which divides into the lateral and medial segments of the middle lobe. Below the origin of the middle lobe is the beginning of the lower lobe bronchus, which almost at once gives off the bron chus to the apical segment of the lower lobe, which passes
Harold Ellis, CBE, MCh, FRCS, was Professor of Surgery at Westminster Medical School until 1989. Since then he has taught anatomy, first in Cambridge and now at Guy’s Hospital, London, UK.
ANAESTHESIA AND INTENSIVE CARE MEDICINE 9:12
513
© 2008 Elsevier Ltd. All rights reserved.
Anatomy
Branches of the bronchial tree Upper lobe Apico-posterior bronchus Anterior bronchus
Upper lobe Apical bronchus Posterior bronchus Anterior bronchus
Lingula Inferior bronchus Superior bronchus Lower lobe Apical bronchus Medial basal (cardiac) bronchus Anterior basal bronchus Lateral basal bronchus Posterior basal bronchus
Lower lobe Apical bronchus Anterior basal bronchus Lateral basal bronchus Posterior basal bronchus
Middle lobe Medial bronchus Lateral bronchus
The right lung
The left lung
Figure 2
Segments of the lung The right lung
Upper lobe Apical bronchus Posterior bronchus Anterior bronchus Middle lobe Medial bronchus Lateral bronchus Lower lobe Medial basal (cardiac) bronchus Apical bronchus Anterior basal bronchus Lateral basal bronchus Posterior basal bronchus
The left lung
Upper lobe Apical bronchus Posterior bronchus Anterior bronchus Lingula Superior bronchus Inferior bronchus Lower lobe Apical bronchus Anterior basal bronchus Lateral basal bronchus Posterior basal bronchus
Figure 3
ANAESTHESIA AND INTENSIVE CARE MEDICINE 9:12
514
© 2008 Elsevier Ltd. All rights reserved.
Anatomy
supply the apical, anterior and posterior segments of the upper lobe, just as on the right side, except that usually the apical and posterior bronchi originate from a common trunk, the apicoposterior bronchus. The inferior division of the left upper lobe bronchus supplies the lingula; this is the tongue-like projection that lies at the antero-inferior part of the upper lobe. This lingu lar bronchus passes downwards, forwards and laterally before bifurcating into a superior and inferior branch. This division into medial and lateral segments is characteristic, in contrast to the upper and lower segments of the comparable middle lobe of the right lung. The bronchi of the left lower lobe, and its segments, resemble those on the right side, except that there is no medial basal (cardiac) branch because the cardiac impression hollows the medial aspect of the left lung. ◆
directly posteriorly from the stem of the main lower lobe bron chus. If an individual is lying on their back, it is into this bron chus that an inhaled foreign body or a retained plug of mucus is likely to fall. About 1.5 cm below the apical bronchus of the lower lobe arises the medial basal, or cardiac, bronchus, which has no equivalent in the left lung, and then, in rapid succession, the anterior basal, lateral basal, and posterior basal bronchi. The last is the largest, and continues the direction of the main lower lobe bronchus. The left lung: the main bronchus on the left side has a course of about 5 cm before giving off the left upper lobe bronchus. This passes laterally for 1 cm, then bifurcates into a superior and infer ior, or lingular, division. The superior division soon divides to
ANAESTHESIA AND INTENSIVE CARE MEDICINE 9:12
515
© 2008 Elsevier Ltd. All rights reserved.
The main and segmental bronchi
Trachea and main bronchi viewed from the front
Harold Ellis
Trachea Anterior bronchus
Abstract
Apico-posterior bronchus
The trachea bifurcates at the level of T4 in the cadaver; in the living subject it descends to T6 in full inspiration. The right main bronchus is wider, shorter and more vertical than the left; therefore more likely to aspirate a foreign body or to be inadvertently entered by a catheter or endotracheal tube. The lungs are divided into bronchopulmonary segments, each with its own blood supply and bronchial branch. The right lung has an upper, middle and lower lobe, the left an upper and lower lobe, the upper having a lingular segment, somewhat equivalent to the right middle lobe but supplied from the upper lobe bronchus. The upper lobe on each side comprises an apical, anterior and posterior segment, the lower lobe an apical and posterior, lateral and anterior basal segment. The right lower lobe also has a small medial basal (cardiac) segment. The right middle lobe has a medial and lateral segment, while the lingula has a superior and inferior segment. The segmental anatomy of the lungs enables segmental resections to be performed and is important in postural drainage of the lungs.
Carina Right main bronchus Upper lobe bronchus Lower part of right main bronchus Middle lobe bronchus Lower lobe bronchus Medial basal bronchus (cardiac)
Apical bronchus
Keywords anatomy; bronchopulmonary; bronchus; lingula; lobe; lower;
Posterior basal bronchus
middle; postural drainage; right; segmental resection; segments; upper
Anterior basal bronchus Lateral basal bronchus Lingula
The main bronchi In the cadaver, the trachea bifurcates at the level of the 4th thor acic vertebra. In the erect individual, in full inspiration, this level lowers to the 6th thoracic vertebra. The right main bronchus is shorter, wider and more vertical than the left (Figure 1). It is shorter because it gives off its upper lobe bronchus after a course of only 2.5 cm, it is wider because it supplies the bulkier lung, and it is more vertical because the left bronchus has to pass later ally under the aortic arch to reach the left lung. Because of this, an inhaled foreign body, the tip of an aspirating catheter, or the end of an endotracheal tube that is too long for the size of the patient is much more likely to pass into the right, rather than the left, bronchus. The right pulmonary artery lies below, and then passes in front of, the right main bronchus, while the azygos vein arches over it. The left main bronchus is double the length of the right. It passes under the aortic arch, to cross in front of the oesophagus and descending aorta, with the left pulmonary artery first above and then in front of it.
Figure 1
The bronchopulmonary segments The lungs are divided functionally into a series of bronchopulmonary segments (Figures 2 and 3), each with its own bron chus and its own blood supply, and with its parenchyma distinct from its adjacent segments. Radiological diagnosis, surgical seg mental resections and the postural drainage of collapsed lung seg ments depend on this segmental anatomy. The main difference between the two lungs is that the lingular branches arise from the left upper lobe bronchus, whereas the middle lobe branches arise from the lower part of the main bronchus on the right. The right lung: the right main bronchus, after a course of 2.5 cm, gives off the upper lobe bronchus, which trifurcates into the api cal, posterior and anterior segmental bronchi. The main bron chus continues for about 3 cm, then gives off the forward and downwardly directed middle lobe bronchus, which divides into the lateral and medial segments of the middle lobe. Below the origin of the middle lobe is the beginning of the lower lobe bronchus, which almost at once gives off the bron chus to the apical segment of the lower lobe, which passes
Harold Ellis, CBE, MCh, FRCS, was Professor of Surgery at Westminster Medical School until 1989. Since then he has taught anatomy, first in Cambridge and now at Guy’s Hospital, London, UK.
ANAESTHESIA AND INTENSIVE CARE MEDICINE 9:12
513
© 2008 Elsevier Ltd. All rights reserved.
Anatomy
Branches of the bronchial tree Upper lobe Apico-posterior bronchus Anterior bronchus
Upper lobe Apical bronchus Posterior bronchus Anterior bronchus
Lingula Inferior bronchus Superior bronchus Lower lobe Apical bronchus Medial basal (cardiac) bronchus Anterior basal bronchus Lateral basal bronchus Posterior basal bronchus
Lower lobe Apical bronchus Anterior basal bronchus Lateral basal bronchus Posterior basal bronchus
Middle lobe Medial bronchus Lateral bronchus
The right lung
The left lung
Figure 2
Segments of the lung The right lung
Upper lobe Apical bronchus Posterior bronchus Anterior bronchus Middle lobe Medial bronchus Lateral bronchus Lower lobe Medial basal (cardiac) bronchus Apical bronchus Anterior basal bronchus Lateral basal bronchus Posterior basal bronchus
The left lung
Upper lobe Apical bronchus Posterior bronchus Anterior bronchus Lingula Superior bronchus Inferior bronchus Lower lobe Apical bronchus Anterior basal bronchus Lateral basal bronchus Posterior basal bronchus
Figure 3
ANAESTHESIA AND INTENSIVE CARE MEDICINE 9:12
514
© 2008 Elsevier Ltd. All rights reserved.
Anatomy
supply the apical, anterior and posterior segments of the upper lobe, just as on the right side, except that usually the apical and posterior bronchi originate from a common trunk, the apicoposterior bronchus. The inferior division of the left upper lobe bronchus supplies the lingula; this is the tongue-like projection that lies at the antero-inferior part of the upper lobe. This lingu lar bronchus passes downwards, forwards and laterally before bifurcating into a superior and inferior branch. This division into medial and lateral segments is characteristic, in contrast to the upper and lower segments of the comparable middle lobe of the right lung. The bronchi of the left lower lobe, and its segments, resemble those on the right side, except that there is no medial basal (cardiac) branch because the cardiac impression hollows the medial aspect of the left lung. ◆
directly posteriorly from the stem of the main lower lobe bron chus. If an individual is lying on their back, it is into this bron chus that an inhaled foreign body or a retained plug of mucus is likely to fall. About 1.5 cm below the apical bronchus of the lower lobe arises the medial basal, or cardiac, bronchus, which has no equivalent in the left lung, and then, in rapid succession, the anterior basal, lateral basal, and posterior basal bronchi. The last is the largest, and continues the direction of the main lower lobe bronchus. The left lung: the main bronchus on the left side has a course of about 5 cm before giving off the left upper lobe bronchus. This passes laterally for 1 cm, then bifurcates into a superior and infer ior, or lingular, division. The superior division soon divides to
ANAESTHESIA AND INTENSIVE CARE MEDICINE 9:12
515
© 2008 Elsevier Ltd. All rights reserved.