Anatomy III: Blood, Cardiovascular and Respiratory Systems

Trachea and Bronchial Tree

Trachea Overview

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Anatomy III: Blood and the
Cardiovascular and Respiratory
Systems
Dr. José Luis Monroy Antón
6 CMLesson 4
Trachea. Bronchial tree
Vessels of the tracheobronchial tree

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2Trachea
•
It begins at the larynx (level of C6)
. It ends at the Carina (level of sternal
angle), where it divides into right and left
main bronchi
•
Its main function is to transport air to the
lungs and from the lungs
•
Its epithelium can push the mucus with
waste towards the pharynx, for expulsion
through the mouth
•
Diameter about 3 cm

Trachea Topography

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3Topography of the trachea
•
Laterally:
- Superior part: common carotid arteries and
thyroid gland
- Inferior part: jugular veins and vagus
nerves, pleura, superior vena cava
· Posteriorly: esophagus and recurrent laryngeal
nerves
· Anteriorly: infrahioid muscles, isthmus of the
thyroid, left brachiocephalic vein
Tokubb

Trachea Structure

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4Trachea
. The trachea is a fibrocartilaginous tube at the midline of the neck
•
It has incomplete cartilaginous rings that keep the trachea open
. The incomplete part is the flat posterior zone, that is adjacent to the
esophagus. Here, the involuntary smooth trachealis muscles
complete the circumference of the ring (membranous rings)
· If you see a tracheal deviation from the midline at the radiography, it
may be a sign of a pathological process that diverts it
Tracheal trauma normally affects the esophagus due to its closeness
•

Trachea Notches

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5Trachea notches
We can find three notches at the
trachea, due to 3 structures:
· Thyroid print: at the left side, due
to the left lobe of the thyroid,
normally between 2nd to 5th
tracheal ring
Trachea
· Brachiocephalic trunk print: in
the anterior surface
•
Aortic print: at the left side, it
corresponds to the arch of the
aorta crossing from right to left
and from anterior to posterior
Larynx
Thyroid notch
Brachicephalic notch
Right main
bronchus
Aortic notch
Left main
bronchus

Trachea Vessels and Nerves

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6Vessels and nerves of the trachea
· Arterial: small branches from thyroid and bronchial arteries
· Venous: mucous plexus that arises at the external surface of the
trachea and drain into the thyroid and bronchial veins
· Lymphatics: pretracheal and paratracheal lymph nodes
· Nerves: fibers from the pulmonary plexus, which is formed by:
- Sympathetic from the cervical and two first thoracic ganglia
- Parasympathetic from the vagus nerve

Tracheobronchial Tree

Tracheobronchial Tree Overview

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7Tracheobronchial tree
· Tracheobronchial tree is the name that
receive the airway below the larynx
. The trachea is the trunk of this tree, that
bifurcates at the Carina at the transverse
thoracic plane into main bronchi
. The function of the main bronchi is to
conduct the air to its respective lung
· The main bronchi pass inferolaterally to
enter the lungs at the hilum
Trachea
Left main
bronchus
Bronchioles

Right Main Bronchus

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8Tracheobronchial tree
Right main bronchus: bigger than the
left and more vertical. Relations:
· Superior: arch of the azygos vein
· Inferior: right pulmonary veins,
pericardium and right atrium
· Anterior: superior vena cava and
right pulmonary artery
· Posterior: bronchial arteries
O
®

Left Main Bronchus

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9Tracheobronchial tree
Left main bronchus: smaller than the
right and almost horizontal. It passes
below the aortic arch. Relations:
· Superior: aortic arch
· Inferior: left pulmonary veins,
pericardium and left atrium
· Anterior: left pulmonary artery
· Posterior: bronchial arteries and
descending aorta
O
®

Trachea Relations

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10Check the relations of the trachea
Right bronchial artery
(branch from right third
posterior intercostal artery)
Aortic arch
Superior left bronchial artery
Right pulmonary artery
Left pulmonary artery
Bronchial vessels
on posterior surface
of bronchi
Inferior left bronchial artery
Left pulmonary veins
Right pulmonary
veins
Pulmonary trunk
Pulmonary ligament
Thoracic aorta
Esophagus

Secondary Bronchi

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11Secondary bronchi
Also called lobar bronchi: 3 on the right side and 2 on the left. Three layers:
· Bronchial cartilage: here the cartilage does not
have ring shape. It form plates arranged laminarly
around the bronchial airway, as a perichondrium.
The flattened posterior part of the ring disappears
•
Bronchial muscle: smooth muscle fibers forming
oblique spirals, crossing as the laces of a shoe
Adventitia
Smooth mucle
Mucosa
Cartilage
Bronchial wall
•
Mucosa: three kinds of cells:
- Epithelium: pseudostratified ciliated columnar
epithelium
- Goblet cells: produces mucus
- Serous glands: that excrete to the bronchial
lumen
Pseudostratified ciliated epithelium
Lamina propria
+

Trachea, Carina and Lobar Bronchus Comparison

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12Compare the three levels: trachea, carina and lobar bronchus
Carina
Entire trachea
and carina
Carina
Right main
bronchus
Left main
bronchus
Carina
Segmental
bronchi
Right upper lobe
bronchus

Recommended Video

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13Recommended video
· Video of a full bronchoscopy
· Prof. Federico Venuta -
Department of thoracic surgery -
Università di Roma & Umberto I
Policlinico di Roma
•
Available at:
https://www.youtube.com/watch?
V=V9SJVicR9PY
Trachea

Tertiary Bronchi

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14Tertiary bronchi
Also called segmentary bronchi, because they delimite the 10 segments of each lung:
Trachea
Right main
bronchus
Left main
bronchus
Right superior
lobar ("eparterial")
bronchus
Left
superior lobar
bronchus
Right
middle
lobar
bronchus
Left
inferior
lobar
bronchus
Segmental
bronchus
Right
lower
lobar
bronchus
IN
1

Bronchopulmonary Segments

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15Apical
Apical
Anterior
3
Superior
Lateral
Anterobasal
Medial
Medial
basal
Posterobasal
Anterior
view
Lateral
view
Apical
Posterior
Anterior
Anterior
Superior
Medial
Medial
basal
Posterobasal
Anterobasal Laterobasal
Medial
view
Lobes of right lung:
Superior lobe
Apical
Posterior
Anterior
Middle lobe
Lateral
Medial
Inferior lobe
Superior
-
Anterior basal
Medial basal
-
Lateral basal
-
Posterior basal
Medial
Antero
basal
Anterior
Medial
basal
Laterobasal
Posterior
Posterobasal
Inferior
view
Segments of the
Right Lung
Apical
Posterior
Superior
Lateral
Posterobasal
Laterobasal
Anterobasal
Posterobasal
Laterobasal
Anterobasal
Lateral
Medial
Posterior
view
Posterior
AnteriorApical
Apical
Anterior
Post.
Anterior
Superior
Lingular
Superior
Inferior
Lingular
Postero
basal
Anterobasal
Anterior
view
Lingular
Anterobasal
Anterior
Medial
basal
Laterobasal
Postero
basal
Inferior
view
Segments of the
Left Lung
Apical
Anterior
Superior
Superior lingular
Inferior Lingular
Postero
basal
Medial
basal
Laterobasal
Anterobasal
Medial
view
Lobes of left lung:
Superior lobe
Apical
-
Posterior
-
Anterior
Superior
lingular
Inferior
lingular
Inferior lobe
Superior
Anterior basal
-
Medial basal
Lateral basal
Posterior basal
Apical
Post.
Superior
aterobasal
Posterobasal
Posterior
view
Inferior
Lateral
view
Posterobasal
Inferior
Lingular
Anterobasal
LaterobasalWhat are the bronchopulmonary segments?
•
They are the largest
subdivisions of the lungs
after the lobe
•
They have the name of their
corresponding segmental
bronchi
· Their shape is pyramidal,
with the apex looking at the
hilum and the base lying at
the pleural surface
Branch of pulmonary artery
Lateral bronchopulmonary segment
of middle lobe of right lung
Medial bronchopulmonary segment
of middle lobe of right lung

Bronchopulmonary Segments Characteristics

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18What are the bronchopulmonary segments?
. The segments are isolated
form the other thanks to
septa made by connective
tissue, so they are
surgically resectable
independently
•
They are supplied
independently by a
segmental bronchus and a
tertiary branch of the
pulmonary artery
•
They are drained by the
intersegmental parts of
the pulmonary veins
Branch of pulmonary artery
Lateral bronchopulmonary segment
of middle lobe of right lung
Medial bronchopulmonary segment
of middle lobe of right lung

Bronchopulmonary Segment Schematic

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19Simplified
overview of
a segment
Bronchial
arteries
Intrasegmental
Pulmonary
arteries
Bronchial
capillaries
1
Pulmonary vein
(intersegmental)
Pulmonary
vein
Alveolar
capillary
plexus
Septum
Alveolar
sac
(plexus
removed)
Visceral
pleura
Bronchial
artery
branch

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Bronchopulmonary segment
(schematic)
20Bronchioles

Bronchioles Overview

. The bronchioles enter the pulmonary lobules to conduct the oxygen to their bottom
· Bronchioles have a very small caliber, their cartilage has disappeared and their
epithelium is cylindrical and ciliated
Tributary of pulmonary vein
Conducting
Lymphatic vessels
Pulmonary artery
Bronchioles
1
Terminal
Bronchiole
Tertiary
structures
Respiratory
Bronchial artery
Duct
Alveolar
Sac
Surface
of lung
Alveolus
Visceral pleura

Intralobular and Terminal Bronchioles

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21Bronchioles
Intralobular/conducting bronchiole : the
segmental bronchi divides in about 20
intralobular bronchioles without cartilage in
their walls, and without glands or alveoli in
their mucosa
Each pulmonary lobule has a small hilum,
the entry of:
· The bronchiole
· The lobular artery
Each intralobular bronchiole divides into 5-7
branches called terminal bronchioles
Terminal
bronchiole
Respiratory
bronchiole
Alveolar
sac
Alveolar
duct opening
into alveolar
sac

Respiratory Bronchioles and Alveoli

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22Bronchioles
Intralobular/conducting bronchiole
•
Terminal bronchiole: "terminal" because
they will give the:
- Respiratory bronchiole: very
profuse division, with 2-11 outgrowths
on their walls called alveolar ducts,
the openings of the alveolar sacs
· Alveoli: where gas exchange
occurs. We have more than 300
million of alveoli
Terminal
bronchiole
Respiratory
bronchiole
Alveolar
sac
Alveolar
duct opening
into alveolar
sac

Alveoli Structure and Function

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23Alveoli
•
They have a very thin wall that allows the
exchange of O2 and CO2
· The opening of each alveolus is encircled by a
smooth muscle cell
. Type I pneumocytes: they form 95% of the
alveolar surface. They form occluding junctions
with each other to prevent the entry of
extracellular fluid from the intra-alveolar
connective tissue into the alveolus
•
Type II pneumocytes: cuboidal cells with
lamellar bodies that discharge the surfactant
into the lumen for reduce the surface tension
and keep the alveolar patency
- They create and reabsorb surfactant
continuously
- They can develop into more pneumocytes
(I and II)
Smooth muscle
fibers
Pulmonary
artery (carrying
deoxygenated
blood)
Intra-alveolar
septum
Respiratory
bronchiole
a
0
Respiratory
bronchiole
Pulmonary vein
(carrying
oxygenated
blood)
Alveolar duct
Alveolar
pore
Alveoli
Alveolar elastin
network
Alveolar capillary network
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24