Pleura

Pleura

1. Layers

   • Visceral
     • inner layer which covers the lung & lines its fissures
   • Pariatal
     • lines thoracic wall from inside & lines chest wall & covers the mediastinum.
   • The visceral and parietal pleurae are continuous together around the root of the lung.

2. Pulmonary Ligament

   • The pleura extends downwards as a fold below the root called the pulmonary ligament.
   • Functions : Provides DEAD SPACE into which the :
     • Lung root descends with descent of the diaphragm.
     • Pulmonary veins can expand (exercise).

3. Pleural Cavity

   • The closed cavity between the visceral and parietal pleurae
   • contains a thin film of fluid (PLEURAL FLUID) and encloses the lung.
     • Lubricates the pleural surfaces and allows the layers of pleura to slide smoothly over each other during respiration
   • Inflammation of the pleura makes the pleural surfaces rough. The resulting friction (pleural rub) is detectable with a stethoscope.

4. Visceral Pleura

   • Absent in :
     • Hilum of the Lung
     • Between the 2 layers of pulmonary ligament

5. Pariatal

   • Costal Pleura
     • Lining the :
       • Sternum
       • Ribs
       • Costal Cartilages
       • Intercostal spaces
       • Sides of vertebral column
   • Diaphragmatic pleura
   • Cervical Pleura
     • covers the apex of the lung.
     • It is attached above by the suprapleural membrane
   • Mediastinal Pleura
     • which covers the sides of the mediastinum.
     • Relations: as mediastinal surface of the lungs.

6. Pleural Recesses

   • They are narrow extensions of the pleural cavity.
   • Allows the lungs to expand during deep inspiration.
   • Sites
     • Costodiaphragmatic recess {Costophrenic angle}
       • lies between the costal & diaphragmatic pleura along the INFERIOR MARGIN of the pleura
       • Accumulation of fluid in the pleural cavity , the fluid tends to gravitate towards the recesses >> obliterates the costophrenic angle will cause an opacity which obliterates the angle. Pleural Effusion { HYDROTHORAX }
       • In thoracocentesis, inserting the needle into the 9th intercostal space in the mid-axillary line during expiration will avoid the inferior border of the lung.
     • Costomediastinal recess
       • lies between the costal and mediastinal pleura along the anterior margin of the pleura
       • Overlies the heart.
       • Lies at the anterior ends of the left 4th and 5th intercostal spaces.
       • During full inspiration it becomes occupied by the lingula of the left lung.