Download anatomy of pleura

Dr. Mujahid Khan
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The pleurae and lungs lie on either side of the
mediastinum within the chest cavity
Each pleura has two parts:
Parietal layer
Visceral layer
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It lines the thoracic wall
Covers the thoracic surface of the diaphragm
and the lateral aspect of the mediastinum
Extends into the root of the neck to line the
undersurface of the suprapleural membrane at
the thoracic outlet
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It completely covers the outer surfaces of the
lungs
Extends into the depths of the interlobar
fissures
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The two layers continuous with one another by
means of a cuff of pleura
This cuff surrounds the structures entering and
leaving the lung at the hilum of each lung
Pleural cuff hangs down as a loose fold called
the pulmonary ligament
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The parietal and visceral layers are separated from
one another by a slitlike space called pleural cavity
Clinicians use the term pleural space instead of the
anatomic term pleural cavity
Pleural cavity contains thin film of tissue fluid
called pleural fluid
Fluid permits the two layers to move on each other
with the minimum of friction
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Parietal pleura is divided into the region in
which it lies or the surface that it covers
The cervical pleura extends up into the neck
It lines the undersurface of the suprapleural
membrane
It reaches a level 1 to 1.5 in. (2.5 to 4 cm) above
the medial third of the clavicle
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It lines the inner surfaces of:
The ribs
The costal cartilages
The intercostal spaces
The sides of the vertebral bodies
The back of the sternum
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It covers the thoracic surface of the diaphragm
In quiet respiration, the costal and
diaphragmatic pleurae are in apposition to
each other below the lower border of the lung
Costal and diaphragmatic pleurae separate in
deep inspiration
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The lower area of the pleural cavity into which
the lung expands on inspiration is referred to
as the costodiaphragmatic recess
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It covers and forms the lateral boundary of the
mediastinum
It is reflected as a cuff around the vessels and bronchi
at the hilum of the lung
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Then continuous with the visceral pleura
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Each lung lies free except at the hilum
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it is attached to the blood vessels and bronchi that
constitute the lung root
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During full inspiration the lungs expand and
fill the pleural cavities
During quiet inspiration the lungs do not fully
occupy the pleural cavities at four sites
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The right and left costodiaphragmatic recesses
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The right and left costomediastinal recesses
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Are slitlike spaces between the costal and
diaphragmatic parietal pleurae
Separated only by a capillary layer of pleural fluid
During inspiration, the lower margins of the lungs
descend into the recesses
During expiration, the lower margins of the lungs
ascend so that the costal and diaphragmatic pleurae
come together again
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Are situated along the anterior margins of the pleura
They are slitlike spaces between the costal and the
mediastinal parietal pleurae
Separated by a capillary layer of pleural fluid
During inspiration and expiration, the anterior borders
of the lungs slide in and out of the recesses
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The parietal pleura is sensitive to pain, temperature,
touch and pressure, and is supplied as follows:
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 intercostal nerves
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The visceral pleura covering the lungs is
sensitive to stretch
It is insensitive to common sensations such as
pain and touch
It receives an autonomic nerve supply from the
pulmonary plexus
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The pleural space normally contains 5 to 10 ml of clear
fluid
It lubricates the opposing surfaces of the visceral and
parietal pleurae during respiration
The formation of the fluid results from hydrostatic and
osmotic pressures between the capillaries
The pleural fluid is normally absorbed into the
capillaries of the visceral pleura
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Any condition that increases the production of the
fluid or impairs the drainage of the fluid 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 percussion over the effusion
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Inflammation of the pleura secondary to
inflammation of the lung called pneumonia
Pleural surfaces become coated with
inflammatory exudate, causing the surfaces to
be roughened
Produces friction, and a pleural rub
It can be heard with the stethoscope on
inspiration and expiration
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Often the exudate becomes invaded by
fibroblasts
That lay down collagen and bind the visceral
pleura to the parietal pleura
Forms pleural adhesions