ANATOMY OF
TRACHEOBRONCHIAL TREE
PRESENTED BY- Dr. CHITRA
MODERATOR-Dr.AJAY SOOD
Respiratory System
TRACHEA
It is a cartilaginous and membranous
tube
 EXTENT - from 6th cervical vertebra till the
body of 5th thoracic vertebra
 During expiration the bifurcation rises by one
vertebral level and during inspiration may be
lowered as far as 6th thoracic vertebra
 LENGTH - 11cm
 DIAMETER - 2 to 2.5cm
 CHILDREN - smaller, deeper, more moveable
STRUCTURE
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CARTILAGES-16to20 in no.,each forms an incomplete
ring,which occupies anterior two third of circumference of
trachea
Are placed horizontally above each other,separated by
narrow intervals
4mm deep and 1mm thick
Outer surface is flattened in vertical direction and convex
from inner side
Highly elastic,but may calcify in later stages
FIRST TRACHEAL CARTILAGE-broader,divided connected
to lower end of cricoid by cricotracheal ligament
LAST TRACHEAL CARTILAGE-thick and broad in midlle,
lower border is prolonged to a triangular hook shaped
process which curves downward and backward between
two bronchi
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FIBROUS MEMBRANE-cartilages are enclosed in an
elastic fibrous membrane which consists of two
layers,one passes over the outer surface the other one
over the inner surface
At upper and lower margins they blend together to form
a single membrane
MUSCULAR TISSUES-two layers of non –striated muscles
longitudinal and transeverse
Longitudinal fibres are external,consist of few scattered
bundles only
Transeverse fibers(trachealis muscle) are internal,extends
between the end of cartilages
MUCUS MEMBRANE-continous above with larynx and
below with bronchus
 Consist of areolar and lymphoid tissue,basement
membrane,supporting stratified epithelium ,surface layer
of which is columnar and ciliated
 Beneath basement membrane there is a layer of
longitudinal elastic fibre
 Submucus layer,composed of loose meshwork of
connective tissue
VESSELS AND NERVES ARTERIAL SUPPLY-Inferior thyroid arteries
 NERVE SUPPLY-vagus nerve,recurrent nerve,sympathetic
nerves
RIGHT BRONCHUS
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2.5cm long
Wider,shorter,more
vertical
Divides into EPARTERIAL
and HYPARTERIAL
BRONCHUS based on
right pulmonary artery
RIGHT UPPER LOBE BRONCHUS
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It divides into three segmental bronchi which supply
apical,anterior and posterior segments of upper lobe
APICAL SEGMENTAL BRONCHUS-divides into apical
and anterior subsegmental branches
POSTERIOR SEGMENTAL BRONCHUS-divides into
lateral and anterior subsegmental branches. It serves the
posteroinferior part of superior lobe of lung
ANTERIOR SEGMENTAL BRONCHUS-runs
anteroinferiorly to supply rest of the part of upper
bronchus. Divides into lateral and anterior subsegmental
branches
RIGHT MIDDLE LOBE BRONCHUS
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Divides into lateral and medial subsegments
RIGHT LOWER LOBE BRONCHUS
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Continuation of principal stem beyond the origin of
middle lobe bronchus
Supplies 5 segments of the lung
Apical segmental bronchus
Medial basal segmental bronchus
Anterior basal segmental bronchus
Lateral and posterior basal segmental bronchus
LEFT BRONCHUS
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5cm in length
Smaller in caliber
Enters the lung opposite 6th thoracic vertebra
RELATIONS-passes beneath the aortic arch,crosses in
front of oesophagus,thoracic duct,descending aorta,has
left pulmonary artery at first above and then in front
LEFT UPPER LOBE BRONCHUS
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Cranially it divides into anterior ,apical and posterior
segmental branches
Caudally into superior and inferior lingual branches
LEFT LOWER LOBE BRONCHUS
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Divides into apical segmental bronchus,medial
basal,anterior basal,lateral and posterior basal branches
BRONCHI
• Right bronchus
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– Wider
– More vertical
– shorter
– Supported by C
shaped cartilages
– 20-30 degree angle
– First generation
• Left bronchus
– Narrower
– More angular
– Longer
– Supported by C
shaped cartilages
– 40-60 degree angle
– First generation
CLINICAL SIGNIFICANCE
 Right main bronchus is more in line with trachea
 Inhaled foreign bodies and gastric contents enter
right bronchial tree
 If patient is lying on his side,lateral subsegments of
anterior and posterior segments are more likely
to get such material
 If patient is supine,then apical segmental bronchus
which arise from right or left lower lobe bronchus
is the most common part of lung for the aspirated
material to collect
BRONCHOPULMONARY SEGMENTS
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Anatomic,functional and
surgical units of lung
23 divisons or
generations are involved
in dichotomous
division,starting from
trachea till alveolar sacs
Each lobar
bronchus(secondary
bronchus) gives off
branches called
segmental
bronchus(tertiary
bronchus)
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As bronchi become smaller, cartilages also become
smaller and fewer in no
Bronchioles are formed which are less then 1mm
in dia,no cartilages and lined by ciliated columnar
epithelium
Divide to form terminal bronchioles,which show
delicate outpouchings from their wall
These are respiratory bronchioles,dia is
0.5mm,they end by branching into alveolar ducts
Each alveolar sac consist
of around 17 alveoli
 Each alveolus surrounded
by rich network of blood
capillaries
 Gas exchange primarily
occurs on thin side of
alveolocapillary
membrane,thick side
provides structural
support
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ALVEOLI
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Type I pneumocyteslarge flattened cells,
present a very thin
diffusion barrier for
gases
Type II pneumocytessecretes
surfactant,which
decreases the surface
tension between thin
alveolar walls
macrophages
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Subdivision of lung
lobe
Pyramid shaped,apex
towards lung root
Surrounded by
connective tissue
Segmental
bronchus,segmental
artery,lymph vessels
and autonomic
nerves
Segmental vein lies
between adjacent
segments
BLOOD SUPPLY OF LUNGS
 By bronchial arteries which are branches of
descending aorta
NERVE SUPPLY OF LUNGS
 Pulmonary plexus-efferent and afferent
autonomic nerve fibres
 Sympathetic efferent fibres produce
bronchodilation and vasoconstriction
 Parasympathetic efferent produces
bronchoconstriction,vasodilation,increase
glandular secretions