Lung segments and CT
Bronchoscopy views
Fiberoptic Bronchoscopy for Positioning Double-Lumen Tubes and Bronchial Blockers
https://link.springer.com/chapter/10.1007/978-3-030-00859-8_17
Fiberoptic Bronchoscopy for Positioning Double-Lumen Tubes and Bronchial Blockers
anatomy
Lobar and Segmental Bronchi
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Right upper lobe bronchus
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Apical segmental bronchus (B1)
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Posterior segmental bronchus (B2)
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Anterior segmental bronchus (B3)
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Middle lobe bronchus
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Lateral segmental bronchus (B4)
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Medial segmental bronchus (B5)
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Right lower lobe bronchus
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Superior segmental bronchus (B6)
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Basilar segmental bronchi
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Medial basilar segmental bronchus (B7)
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Anterior basilar segmental bronchus (B8)
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Lateral basilar segmental bronchus (B9)
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Posterior basilar segmental bronchus (B10)
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Left upper lobe bronchus
- ○
Apical-posterior segmental bronchus (apicoposterior) (B1+2)
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Anterior segmental bronchus (B3)
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Lingular bronchi
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Superior lingular segmental bronchus (B4)
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Inferior lingular segmental bronchus (B5)
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Left lower lobe bronchus
- ○
Superior segmental bronchus (B6)
- ○
Basilar segmental bronchi
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Anteromedial basilar segmental bronchus (B7+8)
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Lateral basilar segmental bronchus (B9)
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Posterior basilar segmental bronchus (B10)
Gross anatomy
The trachea divides at the carina forming the left and right main stem bronchi which enter the lung substance to divide further. This initial division is into secondary or lobar bronchi, but subsequent divisions give rise to smaller and smaller bronchi and bronchioles until the smallest bronchioles connect to the innumerable alveoli.
Each segment has its own pulmonary arterial branch and thus, the bronchopulmonary segment is a portion of lung supplied by its own bronchus and artery. Each segment is functionally and anatomically discrete allowing a single segment to be surgically resected without affecting its neighboring segments.
There is some form of segmental symmetry between the right and left lungs, even though the left lung is smaller and only contains two lobes. In general, each lung has 10 segments: the upper lobes contain 3 segments, the middle lobe / lingula 2 and the lower lobes 5. Bilaterally, the upper lobes have apical, posterior and anterior segments and the lower lobes superior (apical) and 4 basal segments (anterior, medial, posterior and lateral). With this basic symmetric anatomy shared between the lungs, there are a few differences that can be described:
the middle lobe on the right has 2 segments: medial and lateral (easy to remember - middle lobe, medial and lateral).
the lingula on the left is part of the left upper lobe and is the equivalent of the middle lobe on the right, and hence it has 2 segments, but in this case, it is divided into superior and inferior segments.
there are 2 regions of the left lung in which 2 segments are joined as 1 as they have a common tertiary (segmental) bronchus:
Right lung
The right lung is subdivided into three lobes with ten segments. The notation in brackets refers to the Boyden classification of bronchi.
apical segment (B1)
posterior segment (B2)
anterior segment (B3)
right middle lobe (or more correctly - just middle lobe)
lateral segment (B4)
medial segment (B5)
superior segment (B6)
medial segment (B7)
anterior segment (B8)
lateral segment (B9)
posterior segment (B10)
Left lung
The left lung is subdivided into two lobes and thereby, into eight segments. The notation in brackets refers to the Boyden classification of bronchi.
apicoposterior segment (B1/2)
anterior segment (B3)
superior segment (B6)
anteromedial segment (B7/8)
lateral segment (B9)
posterior segment (B10)
Useful mnemonic to remember the bronchopulmonary segments are:
A PALM Seed Makes Another Little Palm (right lung)
ASIA ALPS (left lung)
Variant anatomy
Dave Pilcher’s 4 rules for finding where you are:
- the trachea is D shaped, the flat wall is posterior
- the RML bronchus is anterior
- the apical (aka superior) segmental bronchi of the lower lobes are posterior
- if in doubt, go back to the carina
ENDOTRACHEAL TUBE
- via adaptor
- clear plastic with markings on ETT
- Murphy’s eye
TRACHEA
- mucous membranes
- anterior and lateral walls: cartilaginous ‘U’ shaped rings connected by connective tissue
- posterior wall: muscle (trachealis, par membranaceus)
- length: 10-15c in adults (cricoid -> bifurcation)
- diameter: 19-22mm
CARINA
- cartilaginous ring that runs anterior-posteriorly between to main bronchi
- lumen narrows slightly as it progresses towards the carina
RIGHT MAIN BRONCHUS
- more vertical orientation than left
- bronchus intermedius directly ahead
- 1-2cm in is the RIGHT UPPER LOBE BRONCHUS @ 0300
RIGHT UPPER LOBE BRONCHUS
- trifurcation: APICAL, ANTERIOR AND POSTERIOR SEGMENTS
- this is the only place that has 3 orifices
- 1/250 people have their RIGHT UPPER LOBE BRONCHUS coming directory off CARINA
RIGHT BRONCHUS INTERMEDIUS
- come back into RIGHT MAIN BRONCHUS
- identify the RIGHT MIDDLE and LOWER LOBE BRONCHI
RIGHT MIDDLE BRONCHUS
- seen at 1200
- D shape
- MEDIAL and LATERAL SEGMENTS
RIGHT LOWER LOBE
- APICAL SEGMENT @ 0600
- four basal segments (MEDIAL, LATERAL, ANTERIOR and POSTERIOR)
-> withdraw back into trachea
LEFT MAIN BRONCHUS
- lies more horizontal than RIGHT MAIN BRONCHUS
- it is longer and divides into LEFT UPPER and LEFT LOWER LOBE BRONCHI
LEFT UPPER LOBE BRONCHUS
- divides into SUPERIOR and LINGULAR DIVISION @ 0900
- SUPERIOR: gives rise to APICOPOSTERIOR and ANTERIOR segments
- LINGULA: gives rise to the SUPERIOR and INFERIOR segments
LEFT LOWER LOBE BRONCHUS
- APICAL SEGMENT @ 0600
- 3 BASAL SEGMENTS (LATERAL, ANTERIOR and POSTERIOR)
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