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‫بسم هللا الرمحن الرحيم‬
Thoracic Cavity
Thoracic Cavity
- The thoracic cavity
consists of:
I. Lung and its pleura:
on each side.
II. Mediastinum: In
the middle part.
- The mediastinum
contains the heart,
great vessels, and
other structures.
Pleura
Definition:
- It is a closed serous sac which is invaginated by the
lung from its medial side.
Layers:
I. Visceral layer ----------------- Lines the surfaces and
fissures of the lung.
II. Parietal layer ---------------- Lines the thoracic wall
and other structures.
Pleura
Layers:
I. Visceral layer: Lines the
surfaces and fissures of
the lung.
II. Parietal layer: Lines
the thoracic wall and
other structures.
- Between both layers, there
is a small cavity called
the pleural cavity which
contains minimal serous
fluid.
Parts of the parietal pleura:
1. Cervical pleura:
protrudes through the
thoracic inlet to the neck.
2. Costo-vertebral pleura:
covers the inner aspect of
the thoracic wall.
3. Mediastinal pleura:
covers the side of the
mediastinum.
4. Diaphragmatic pleura:
covers the upper surface of
the diaphragm.
Suprapleural membrane
-The cervical pleura is
covered by a fibrous
membrane spreading
fanwise from the
seventh cervical
transverse process to
the inner border of
the first rib.
Pleural recesses
1- Costo-mediastinal Recess 1
- It lies behind the sternum
between the front of the
thoracic wall and the
mediastinum along the
anterior margin of the
pleura.
2- Costo-diaphragmatic
2
Recess:
-It lies between the thoracic
wall and the diaphragm
along the lower margin of
the pleura.
Surface anatomy of parietal
pleural
(1 inch)
Right pleura
(1 inch)
Left pleura
1-Apex of lung:
It lies one inch above the medial end of the clavicle.
2-A point behind the sternal angle close to the middle line at the level
of the second costal cartilage.
3-A point behind the sternum close to the middle line at the level of
the fourth costal cartilage.
4- On the right side:
A point behind the sternum close to the middle line at the level of
the sixth costal cartilage.
On the left side:
A point behind the sixth costal cartilage 2 cm from the sternum.
5-A point on the eighth rib in the mid-clavicular line.
6-A point on the tenth rib in the mid-axillary line.
7-A point just below the medial end of the twelfth rib opposite the
twelfth thoracic spine.
Nerve supply of the pleura
Parietal pleura:
1-Costal pleura and peripheral diaphragmatic pleura:
Intercostal nerves .
2-Mediastinal and central diaphragmatic pleura :
Phrenic nerves.
Viseral pleura: Not sensitive (has autonomic nerve supply).
Arterial supply
Partial Pleura:
1. Intercostal arteries.
2. Internal thoracic artery.
3. Musculo-phrenic and pericardiaco-phrenic arteries.
Visceral Pleura:
- Bronchial arteries.
Applied anatomy
- Pain due to irritation of the costal and peripheral
diaphragmatic pleura is referred to the thoracic or
abdominal walls along the intercostal nerves.
- Pain due to irritation of the mediastinal and
central diaphragmatic pleura is referred to the
root of the neck and shoulder, because they are
supplied by the same spinal segments through
the supra clavicular nerves (C. 3,4).
Lung
* Each lung has an
apex, a base, 3
borders
( anterior,
posterior and
inferior), and
2 surfaces
(Medial and
costal).
*Medial surface
(Mediastinal
&vertebral )
Apex And Base of the lung
 Apex:
It extends up 1 inch
above and behind the
medial third of the
clavicle.
 Base:
It is concave in shape .
It is related to:
1- Diaphragmatic pleura.
2- Right copula of the
diaphragm.
3- Liver (right lung) .
Liver, stomach (fundus),
and spleen (left lung).
Relations of the apex of lung
Anteriorly:
- Subclavian artery.
Posteriorly:
- The three structures which
are related to the neck of
the first rib (from medial
to lateral):
1. Stellate ganglion.
2. Superior intercostal
artery.
3. Ventral ramus of 1st
thoracic n.
Borders of the lung
A. Anterior border
It is a sharp border and occupies
the costo-mediastinal recess of
the pleura.
The lower part of the anterior
border of the left lung contains
the cardiac notch (just below
the cardiac notch there is a
projection called the lingula).
B. Posterior border
It is a rounded border and
occupies the para-vertebral
gutter.
C. Inferior border
It protrudes through the costodiaphragmatic recess.
Costal surface of left lung
Surfaces of the lung
A. Costal surface
It is related to the thoracic
wall and costal pleura.
B.Medial surface:
1-Vertebral surface related
to paravertebral gutter.
2-Mediastinal surface
contains the hilum of the
lung and is related to
grooves and impressions.
Vertebral
surface
. Costal surface of the lungs
Right lung
Left lung
Lobes &Fissures of the lungs
Right lung
- The right lung is divided into
three lobes(superior, middle,
and inferior) by :
1-Oblique fissure:
It begins at the posterior border of
the lung opposite the fourth
thoracic spine & ends at the
inferior border opposite the six
costo-chondral junction.
2-Transverse fissure :
It begins at the anterior border
opposite the fourth costal
cartilage.
Left lung
- The left lung is divided into two
lobes (superior and inferior) by
the oblique fissure.
* Oblique fissure (surface
anatomy)
- It begins at the posterior border
of the lung opposite the third
thoracic spine (1 inch lateral to
the spine) & ends at the inferior
border opposite the six costochondral junction
Mediastinal Surface of the Right Lung
1- Cardiac impression, related to
right atrium.
2- Superior vena cava.
3- Inferior vena cava.
4- Right innominate vein.
5- Arch of azygos vein.
6- Azygos vein.
7- Oesophagus.
8- Trachea.
9- Right vagus nerve.
10- Right phrenic nerve.
11- Ascending aorta & thymus.
Mediastinal Surface of the Left Lung
1- Cardiac impression, related to
left ventricle.
2- Arch of the aorta.
3- Descending aorta.
4- Left common carotid artery.
5- Left subclavian artery.
6- Oesophagus (two sites).
7- Thoracic duct.
8- Left vagus nerve.
9- Left phrenic nerve.
10- Pulmonary trunk and thymus.
Hilum of the lungs
* It gives passage to the
structures forming the
root of the lung.
1. Bronchus
2. Pulmonary artery
3. Pulmonary veins
4. Hilar lymph nodes.
5. Bronchial vessels.
6. Pulmonary plexuses
(anterior and posterior).
7. Pulmonary ligament .
Hilum of left
lung
Hilum of
right lung
Hilum of left
lung
- One bronchus( most
posterior structure).
-Pulmonary artery
(anterior and above the
bronchus
-Two pulmonary veins
( most anterior and
inferior structures).
Hilum of right
lung
- Two Bronchi (Eparterial
and hyparterial)( most
posterior structure).
- Pulmonary artery
(anterior and in between
the two bronchi).
- Two pulmonary veins
(most anterior and
inferior structures).
Difference between the right and left
lungs
1. Size and
weight
Right Lung
- Larger and heavier.
Left Lung
- Smaller and lighter.
2. Length and - Shorter and wider.
breadth
- Longer and narrower.
3. Lobes and
fissures
- Two fissures.
- Three lobes.
- One fissure.
- Two lobes.
4. Anterior
border
- No cardiac notch.
- Cardiac notch&
lingula.
5. Hilum
Broncho-pulmonary segments
- The trachea divides into right and left
main bronchi, with more division of the
main bronchi it gives rise to lobar then
segmental bronchi.
- Each segmental bronchus is distributed to a
localized part of lung tissue forming what is
called the broncho-pulmonary segments.
- The right bronchus divides into: 1- superior
lobar bronchus and 2-middle and
inferior lobar bronchus.
Segmental branches of the bronchi
Superior lobar
bronchus
1. Apical 2. Anterior 3.
Posterior
Middle lobar
bronchus
Inferior lobar
bronchus
4. Medial
1. Apical 2. Anterior 3. Posterior
4. Sup. lingular 5. Inf. lingular
5. Lateral
6. Apical basal 7. Medial basal
6. Apical basal
8. Lateral basal 9. Anterior basal 7. Medial basal 8. Lateral basal
10. Posterior basal
9. Anterior basal 10. Posterior basal
Broncho-pulmonary segments
Broncho-pulmonary segments
Right lung
Superior 1. Apical 2. Anterior
lobe
3. Posterior
Middle
lobe
4. Medial
Left lung
1. Apical 2. Anterior
3. Posterior 4. Sup. lingular
5. Inf. lingular
5. Lateral
Inferior 6. Apical basal
lobe
7. Medial basal
8. Lateral basal
9. Anterior basal
10. Posterior basal
6. Apical basal
7. Medial basal
8. Lateral basal
9. Anterior basal
10. Posterior basal
Surface anatomy of the lung (and
visceral pleura):
-The anterior border is the
same as the parietal pleura.
-The inferior border:
6- A point on the six rib in
the mid-clavicular line.
8- A point on the eighth rib
in the mid-axillary line.
10- A point 1 inch lateral to
the tenth thoracic spine.
Nerve supply
- Both lungs are supplied by the anterior and posterior
pulmonary plexuses.
a. Sympathetic component (2 - 5 thoracic sympathetic
ganglia) Causes broncho-dilatation.
b. Parasympathetic component (vagi) Causes bronchoconstriction + Increases the secretion of the glands.
Blood supply
- The lungs are supplied by the bronchial arteries (
Aorta)and drained by the bronchial veins ( Azygos
system).
Applied anatomy:
1. Cardiac notch of the left lung
- It lies at the medial ends of the 4th and 5th intercostal spaces and related to
the apex of the heart. This area is used for pericardial puncture (to
aspirate fluid from the pericardium), as the introduced needle will not
pass through the pleura or the lung tissue.
2. Stab wounds in the mid-axillary line
a. Above the 8th rib, they lead to injury of the lung and pleura.
b. Between the 10th and 8th rib, they lead to injury of the pleura.
3. Injury of the pleura leads to the followings:
a. Entry of air into the pleural cavity (pneumothorax).
b. Collapse of the lung tissue (atelectasis).
4. Collection of fluids in the pleura
a. Serous Hydro-thorax.
b. Pus  Pyo-thorax.
c. Blood Haemo-thorax.
5. Foreign body entering into the trachea:
- It reaches the right lung because the right main
bronchus is shorter, wider, and more in line with the
trachea.
a. If in the recumbent position:
- It enters the apical segment of the inferior lobe,
because it is the first posterior branch of the bronchial
tree.
c. If in the erect position:
- It enters the posterior basal segment, because it is
the most dependant branch of the bronchial tree
(follows the line of gravity).
Development of the respiratory system
Origin:
*Endoderm of foregut endothelium& glands.
*Splanchnic mesoderm Ms, CT, tracheal rings.
Development of the trachea
Development:
* Ventral border of oesophagus laryngotracheal
diverticulum ( opened cranially& blind caudally)
Elongates, separates from the oesophagus trachea.
Bronchial tree and lung
Development:
*The blind caudal
end of the trachea
dilates gives lung
bud divides into
right and left buds.
Development of right lung
*Right lung bud
three branches:
1-Upper lat. branch
upper lobe
bronchus .
2-Stem lower lobe
bronchus.
3-Lower lat.
Branchmiddle
lobe bronchus.
1-Upper lobe bronchus
three branches (3ry):
a. Apical b. Anterior
c. Posterior
2-Lower lobe bronchus
five branches (3ry):
a. Apical basal
b. Anterior basal
c.Posterior basal
d. Medial basal
e. Lateral basal
3- Middle lobe bronchus
two branches (3ry):
a.Medial
b. Lateral
Development of left lung
*Left lung bud (1ry
) two branches:
1-One lat.
Branch(2ry)
upper lobe
bronchus.
2-Stem lower lobe
bronchus.
1-Upper lobe bronchus
two branches (3ry):
A-Upper:
a. Apicoposterior
b. Anterior
B- Lower ( lingular):
a. Superior b. Inferior
2-Lower lobe bronchus
four branches (3ry):
a. Apical basal
b. Anteromedial basal
c.Posterior basal
d. Lateral basal
• Each tertiary
bronchiole divides
repeatedly 18
generations.
• The final generation
dilates alveoli.
• After birth extra 6
generations until the age
of 8 years 18+ 6= 24
generations.
Congenital anomalies
1- Tracheo-oesophageal fistula:
No separation between the trachea and oesophagus *milk
pass to the lungpneumonia.
*air pass to stomach dilatation resp. impairment.
2- Variation in the number of lobes of the lung.
3- Congenital cysts of a lung:
Due to dilatation of terminal bronchioles.
4- Congenital atelectasis of a lung or lobe:
due to obstruction of 1ry or 2ry bronchioles.
5- Respiratory distress syndrom:
Due to deficiency of surfactants secreted from type II
pneumocytesno dilatation of alveoli death.
Thank You
Prof.: Dr. Wafaa Abdel-Rahman