1.
PLEURA AND PLEURAL CAVITY

2.
PLEURA
 Pleural cavity is lined by
single layer of flat cells,
“mesothelium” and an
associated layer of
supporting connective
tissue; together they form
pleura.

3.
PLEURA
 parietal pleura :pleura
associated with the
walls of a pleural cavity
 visceral pleura :pleura,
which adheres to and
covers the lung: reflects
from the medial wall
and onto the surface of
the lung

4.
DEVELOPMENT OF PLEURA
 each lung bud
invaginates the wall of
coelomic cavity and then
grows to fill a greater
part of the cavity
 lung is covered with
visceral pleura and the
thoracic wall is lined with
parietal pleura
 original coelomic cavity
is reduced to slitlike
space called the pleural
cavity as a result of the
growth of the lung.

5.
SUPRAPLEURAL MEMBRANE
 thickening of connective
tissue that covers the
apex of lung
 extension of
endothoracic fascia that
exists between parietal
pleura and thoracic
cage
 extends between inner
border of first rib and
transverse process of
C7 vertebra
 act as a rigid barrier so
as to prevent changes
in intrathoracic
pressure drawing upon
the contents of the neck

6.
PARTS OF PARIETAL PLEURA
 costal part
 diaphragmatic
part
 mediastinal part
 cervical pleura

7.
CUPOLA OR CERVICAL PART
 the dome-shaped
layer of parietal pleura
lining the cervical
extension of the
pleural cavity
 cervical pleura
extends up into the
neck, lining the
undersurface of the
suprapleural
membrane It reaches
a level 1 to 1.5 in. (2.5
to 4 cm) above the

8.
MEDIASTINAL PART
pleura
covering the
mediastinum

9.
COSTAL PART
 pleura related to the
ribs and intercostal
spaces

10.
DIAPHRAGMATIC PART
 pleura covering
the diaphragm

11.
REFLECTIONS OF PARIETAL PLEURA
 Superiorly: pleural cavity
can project as much as 3-
4 cm above the first
costal cartilage

12.
 Anteriorly: pleural
cavities approach
each other posterior
to the upper part of
the sternum. posterior
to the lower part of
the sternum, the
parietal pleura does
not come as close to
the midline on the left
side

13.
 Inferiorly: In the
midclavicular line, the
pleural cavity extends
inferiorly to rib VIII. In
the midaxillary line, it
extends to rib X. From
this point, the inferior
margin courses
horizontally, to reach
vertebra XII

14.
VISCERAL PLEURA
o Visceral pleura is
continuous with
parietal pleura at the
hilum of each lung.
o The visceral pleura is
firmly attached to the
surface of the lung,
including both
opposed surfaces of
the fissures that divide
the lungs into lobes.

15.
PULMONARY LIGAMENT
 The parietal pleura
surrounding the root
of the lung extends
downwards beyond
the root as a fold
called the pulmonary
ligament.
 The fold contains a
thin layer of loose
areolar tissue with a
few lymphatics

16.
 Actually it provides a dead
space into which the
pulmonary veins can expand
during increased venous
return as in exercise.
 The lung roots can also
descend into it with the
descent of the diaphragm

17.
NERVE SUPPLY OF THE PLEURA
The parietal pleura is
sensitive to pain,
temperature, touch, and
pressure
 The costal pleura is
segmentally supplied by
the intercostal nerves.
 The mediastinal pleura is
supplied by the phrenic
nerve.
 The diaphragmatic pleura
is supplied over the
domes by the phrenic
nerve and around the
periphery by the lower six

18.
NERVE SUPPLY OF VISCERAL
PLEURA
 The visceral pleura
covering the lungs is
sensitive to stretch but
is insensitive to
common sensations
such as pain and
touch.
 It receives an
autonomic nerve
supply from the
pulmonary plexus

19.
BLOOD SUPPLY
 The parietal pleura is
supplied by
intercostal, internal
thoracic and
musculophrenic
arteries.
 The veins drain
mostly into the azygos
and internal thoracic
veins.
 The pulmonary
pleura, like the lung, is
supplied by the
bronchial arteries

20.
LYMPHATIC DRAINAGE
 PARIETAL PLEURA:
The lymphatics drain
into the intercostal,
internal mammary,
posterior mediastinal
and diaphragmatic
nodes.
 VISCERAL PLEURA:
It is drained by the
bronchopulmonary
lymph nodes.

21.
PLEURAL CAVITY
 Two pleural cavities
are situated on either
side of the
mediastinum
 During development,
the lungs grow out of
the mediastinum,
becoming surrounded
by the pleural cavities.
As a result, the outer
surface of each organ
is covered by pleura

22.
 Each lung remains
attached to the
mediastinum by a root
formed by the airway,
pulmonary blood
vessels, lymphatic
tissues, and nerves
 Only a potential space
normally exists
between the visceral
pleura covering lung
and the parietal
pleura lining the wall
of the thoracic cavity

23.
 Two pleural cavities,
one on either side of the
mediastinum, surround
the lungs
 superiorly: extend
above rib I into the root
of the neck
 inferiorly: they extend to
a level just above the
costal margin
 medialy: wall of each
pleural cavity is the
mediastinum

24.
PLEURAL RECESSES
 The lungs do not completely fill the anterior or
posterior inferior regions of the pleural cavities
 This results in recesses in which two layers of
parietal pleura become opposed.
 Expansion of the lungs into these spaces usually
occurs only during forced inspiration
 the recesses provide potential spaces in which
fluids can collect and from which fluids can be
aspirated

25.
 Costomediastinal
recesses: Anteriorly,
where costal pleura is
opposed to
mediastinal pleura.
The largest is on the
left side in the region
overlying the heart.

26.
COSTODIAPHRAGMATIC
RECESS
 The largest and
clinically most
important
recesses
 occur in each
pleural cavity
between the
costal pleura and
diaphragmatic
pleura

27.
 The costodiaphragmatic recesses are the regions
between the inferior margin of the lungs and
inferior margin of the pleural cavities
 They are deepest after forced expiration and
shallowest after forced inspiration

28.
PLEURAL FLUID
 The pleural space
normally contains 5 to
10 mL of clear fluid,
which lubricates the
apposing surfaces of
the visceral and
parietal pleura during
respiratory
movements
 The formation of the
fluid results from
hydrostatic and
osmotic pressures

29.
 Since the hydrostatic
pressures are greater
in the capillaries of the
parietal pleura than in
the capillaries of the
visceral pleura
(pulmonary
circulation), the
pleural fluid is
normally absorbed
into the capillaries of
the visceral pleura.

30.
 Any condition that
increases the production
of the fluid (e.g.,
inflammation, malignancy,
congestive heart disease)
or impairs the drainage of
the fluid (e.g., collapsed
lung) results in the
abnormal accumulation of
fluid, called pleural
effusion
 The presence of 300 mL
of fluid in the
costodiaphragmatic
recess in an adult is
sufficient to enable its
clinical detection
 The clinical signs include
decreased lung expansion
on the side of the effusion,
with decreased breath
sounds and dullness on

31.
 A collection of pus in the
pleural cavity is called
an empyema
 Aspiration of any fluid
from the pleural cavity is
called paracentesis
thoracis.
 It is usually done in the
8th intercostal space in
the midaxillary line. The
needle is passed
through the lower part
of the space to avoid
injury to the principal
neurovascular bundle.

32.
PLEURISY
 Inflammation of the pleura (pleuritis or pleurisy),
secondary to inflammation of the lung, results in
the pleural surfaces becoming coated with
inflammatory exudate, causing the surfaces to be
roughened.
 This roughening produces friction, and a pleural
rub can be heard with the stethoscope on
inspiration and expiration.
 exudate becomes invaded by fibroblasts, which
lay down collagen and bind the visceral pleura to
the parietal pleura, forming pleural adhesions

33.
PNEUMOTHORAX
 As the result of
disease or injury, air
can enter the pleural
cavity from the lungs
or through the chest
wall
 Stab wounds of the
thoracic wall may
pierce the parietal
pleura so that the
pleural cavity is open
to the outside air
 This condition is
called open

34.
PNEUMOTHORAX
 In these circumstances, the air pressure builds up
on the wounded side and pushes the
mediastinum toward the opposite side
 In this situation, a collapsed lung is on the injured
side and the opposite lung is compressed by the
deflected mediastinum. This dangerous condition
is called a tension pneumothorax

35.
 Air in the pleural
cavity associated with
serous fluid is known
as
hydropneumothorax,
associated with pus
as pyopneumothorax,
and associated with
blood as
hemopneumothorax

36.
 In
hemopneumothorax,
blood enters the
pleural cavity. It can
be caused by stab or
bullet wounds to the
chest wall, resulting in
bleeding from blood
vessels in the chest
wall, from vessels in
the chest cavity, or
from a lacerated lung

37.
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