Normally the space between the parietal and visceral pleura is only a potential space and is filled up with thin film of serous fluid. Nevertheless in regions of pleural reflection on to the diaphragm and mediastinum, the space between the parietal and visceral pleura is significantly enlarged. These enlarged regions of pleural cavity are named pleural recesses. They’re crucial for lung growth during deep inspiration. Therefore pleural recesses function as reservation spaces of pleural cavity for the lungs to enlarge during deep inspiration. The recesses of pleura are as follows:.

A. Costodiaphragmatic recesses (left and right ).

B. Costomediastinal recesses (left and right ).

Along with the above recesses of pleura, there are 3 more small recesses, viz.

1. Left and right retroesophageal recesses.

All these are created by the reflection of mediastinal pleura supporting the esophagus. Every recess is believed to be inhabited by a part of the lung, and leads to the retrocardiac space viewed in the radiographs of the chest.

2. Infracardiac recess.

It’s a small recess of right pleural sac which occasionally goes below the inferior vena cava.

Costodiaphragmatic Recess.

It’s found inferiorly between the costal and diaphragmatic pleurae. Vertically it measures about 5 cm and is located opposite the 8th-10th ribs along the midaxillary line. The costodiaphragmatic recesses are the most dependent parts of the pleural cavities, for this reason the fluid of pleural effusion first accumulate at these sites.

Costomediastinal Recess.

It’s found anteriorly between the costal and mediastinal pleurae and is located between sternum and costal cartilages. The right costomediastinal recess is potentially inhabited by the anterior margin of the right lung even during quiet breathing. The left costomediastinal recess is large because of the presence of cardiacnotch in the left lung. Its location can be verified medically by percussion (tapping) of the chest wall. As 1 moves during tap from the area of underlying lung tissue to the area of left costomediastinal recess unoccupied by lung tissue, a change in tone, from resonant to muffled, is discovered. This is termed the area of superficial cardiac dullness.

Clinical Significance

Radiological Appearance Of Pleural Effusion.

When a small volume of fluid accumulates in the costodiaphragmatic recess (pleural effusion) the costodiaphragmatic angle is obliterated (widening of the angle). It’s viewed as radiopaque darkness using a fluid line in Xray chest. This could be the first indicator of pleural effusion. Consequently recesses of pleura are analyzed regularly in the chest radiographs.

The costodiaphragmatic recess can be entered via the 9th and 10th intercostal spaces without penetrating the lung in patient with silent breathing for the reason that it is located opposite 8th– 10th ribs.

Sites Of Expansion Of Pleura Beyond The Thoracic Cage.

There are 5 sites, where pleura goes past the thoracic cage.

These sites are as follows:.

A. On each side in the root of the neck (as domes of pleura).

B. In the right xiphisternal angle.

C. On each side in the costovertebral angle.

The pleura can be punctured accidentally at these sites during surgical procedures.