AIRWAY AND TRACHEA

1. AIRWAY AND LOBES OF THE LUNG
Dr.I.Gurubharath MD PhD Dr.Pooja MD
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2. AIRWAY
The airway consist of the trachea,
bronchi, bronchioles and distal small
airways.
TRACHEA
 9 –12 cm in length.
 It commences at the level of the cricoid
(C6) and bifurcates at the carina(T5)
 Passing from the midline to the right.
 Intrathoracic portion measures 6–9 cm.
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3. Transverse diameter
10–21 mm in women
13–25 mm in men
Sagittal diameter
10–23 mm in women
13–27 mm in men
 There are 12–16 incomplete cartilaginous rings
Lined by Ciliated Pseudo stratified columnar epithelium
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5. BRONCHI
The trachea divides into the main bronchi at the
carina
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7. MAIN BRONCHUS MAIN BRONCHUS
Shorter (2.5cm) Longer(5cm)
More verticle More horizontal
Passes to the root of the lung at T5.
Gives rise to the right upper lobe
bronchus and
lies inferolateral and posterior to the
main pulmonary artery
courses below the arch of the aorta
enters the hilum at T6 and then
courses inferolaterally to the
pulmonary artery.
Enters the hilum of the lung and
continues as the bronchus
intermedius, which courses
obliquely for 3–4 cm and lies
posterior to the right pulmonary
artery
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11. LOBES OF THE LUNG
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12. The lobes of the lung are separated by pleural fissures
RIGHT LUNG LEFT LUNG
RIGHT OBLIQUE (MAJOR) FISSURE
 Separates the right upper &middle lobe from the
right lower lobe
 Runs from T5 through the hilum and contacts the
diaphragm 3–4 cm posterior to the sternum
LEFT OBLIQUE FISSURE
 Separates the upper lobe
from the lower lobe and
follows a similar path,
however it arises from T4 in
75% of patients.
HORIZONTAL (MINOR) FISSURE
 Separates the RUL from RML and runs from the
chest wall between the 4th and 6th rib to the
intralobar artery at the hilum
 Is seen in 50–80% of CXRs.
 On CT it is often seen as an area devoid of
vessels, although is seen on high resolution CT
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16. AZYGOUS FISSURE
 On the right
 Due to an anomalous development of the azygous
vein and terminates in a tear-drop opacity
 Consists of four layers of pleura
 It is variable in size
 Is supplied by the right apical bronchus or its
branches
 Seen in 0.5% of CXR with a male:female ratio of 2:1
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20. INCOMPLETE FISSURES
 Fail to reach the hilum
 Are common (right more than left )
 Occurring in up to 73% of oblique fissures and
60–90% of horizontal fissures
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21. ACCESSORY FISSURES
 Occur in 30–50% of people
 Are seen in 5–10% of CXR, 16–21% of CT
 Fissure separating the left upper lobe from the lingula in 8-18%
SUPERIOR ACCESSORY
 Separates the superior segment of the left lower lobe from the
basal segments
INFERIOR ACCESSORY
 Separates the medial basal segment from the remaing
segements
 This is commoner on the right than the left .
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25. BRONCHOPULMONARY SEGMENTS
 The lobes of the lung are subdivided into broncho-
pulmonary segments, which are supplied by
segmental bronchi, arteries and veins.
The segmental bronchi are named or numbered
(using the Boyden system; 1961)
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26. RIGHT LUNG LEFT LUNG
RIGHT UPPER LOBE
BRONCHUS
1. Apical
2. posterior·
3. anterior
LEFT UPPER LOBE
BRONCHUS
1+2.apico-posterior
3. anterior
4. lingular superior
5. inferior
RIGHT MIDDLE LOBE
BRONCHUS
It courses obliquely anteromedially
and caudally
4.lateral – more horizontal
5.medial
RIGHT LOWER LOBE
BRONCHUS
6.apical (superior)
7.medial basal
8.anterior basal
9.lateral basal
10.posterior basal
LEFT LOWER LOBE
BRONCHUS
6. apical (superior)
7+8.Antero-medial basal
9. lateral basal
10. posterior basal
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30. Acinus
• 6–10 mm
• Contains a respiratory
bronchiole, alveolar duct, sac
and alveoli
• Not seen on CT
• Up to 24 group to form the
secondary pulmonary lobule.
Secondary pulmonary lobule
• Smallest discrete unit – 1–2.5
cm in diameter polyhedron
shape
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31. Accessory tracheal bronchi
Pig bronchus –
An upper lobe or segmental bronchus arising from the right lateral
tracheal wall;
Occurs in 1–2% ·
Accessory cardiac bronchus –
a blind-ending bronchus arising from the right main bronchus or
bronchus intermedius which courses towards the heart
Very rare
Occurs in 0.5%.
DR.I.GURUBHARATH
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REFERENCE:
1. Applied radiological anatomy by Paul butler, 2nd
edition, page no 95-104
2. www.radiopaedia.org

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