To carry out several medical and surgical processes, the wisdom of reflexion of parietal pleura on the surface of chest wall is of great importance to play the role for these processes.

To mention the expression of parietal pleura on the surface, these lines should be observed closely:

Cervical Pleura

It’s marked by a curved line (with convexity pointed upwards) drawn from sternoclavicular joint to the junction of medial third and middle third of the clavicle. The peak of dome of pleura is located 1 inch (2.5) above the medial 1-third of the clavicle.

Anterior (Costomediastinal) Line Of Pleural Reflection

It differs on the 2 sides:

Right Side

On the right side, it goes downwards and medially from the right sternoclavicular joint to the midpoint of the sternal angle, and after that descends vertically up to the midpoint of the xiphisternal joint.

Left Side

On the left side, it goes downwards and medially from the left sternoclavicular joint to the midpoint of the sternal angle, then descends vertically only up to the level of the 4th costal cartilage. It subsequently archesoutwards to get to the sternal margin of sternum and runs downwards a short space lateral to this margin to reach the 6th costal cartilage, about 3 cm from the midline leaving a part of pericardium directly in contact with anterior chest wall (empty area of the heart).

Inferior (Costodiaphragmatic) Line of Pleural Reflection

It enters laterally around the chest wall from the lower limit of the anterior line of pleural reflection. It differs somewhat on 2 sides:.

Right Side

On the right side, the line of reflection begins with the xiphisternal joint or behind the xiphoid process and crosses the 8th rib in the midclavicular line, 10th rib in the midaxillary line, and 12th rib in the lateral border of the erector spinae muscle, 2 cm lateral to the spine of T12 vertebra.

Left Side

On the left side, the line of reflection begins at the level of the 6th costal cartilage, about 2 cm lateral to the midline. Afterward it follows precisely the same course as on the right side.

Posterior (Costovertebral) Line of Pleural Reflection

Itascends from the ending of the inferior line, 2 cm lateral to the T12 spine along the vertebral column to the stage,2 cm lateral to the spine of C 7 vertebra. The costal pleura becomes mediastinal pleura along this line.

The inferior margin of the lung enters more horizontally than the inferior margin of the pleura. Thus, it crosses the 6th rib in the midclavicular line, 8th rib in the midaxillary line, and 10th rib in the lateral border of the erector spine.

The ribs crossed by inferior margin of the lung and pleura in midclavicular line, mid axillary line, and lateral to erector spine are compared below:

  • Inferior margin of lung: 6th rib, 8th rib, and 10th rib
  • Inferior margin of pleura: 8th rib, 10th rib, and 12th rib