1. ANATOMY OF PLEURA
Dr. Mujahid Khan

2. Location
The pleurae and lungs lie on either side of the mediastinum within the chest cavity
Each pleura has two parts:
Parietal layer
Visceral layer

4. Parietal Layer 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

6. Visceral Layer It completely covers the outer surfaces of the lungs
Extends into the depths of the interlobar fissures

7. Pleural Cuff
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

9. Pleural Cavity
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

11. Cervical Pleura
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

13. Costal Pleura 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

15. Diaphragmatic Pleura 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

17. Costodiaphragmatic Recess
The lower area of the pleural cavity into which the lung expands on inspiration is referred to as the costodiaphragmatic recess

18. Mediastinal Pleura
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
Then continuous with the visceral pleura
Each lung lies free except at the hilum
it is attached to the blood vessels and bronchi that constitute the lung root

20. Mediastinal Pleura
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
The right and left costodiaphragmatic recesses
The right and left costomediastinal recesses

21. Costodiaphragmatic recesses
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

23. Costomediastinal Recesses
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

25. Nerve Supply
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

26. Nerve Supply
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

27. Pleural Fluid
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

28. Pleural Fluid
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

30. Pleuricy
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

31. Pleuricy Often the exudate becomes invaded by fibroblasts
That lay down collagen and bind the visceral pleura to the parietal pleura
Forms pleural adhesions