PLEURA (from Greek pleura - rib, side), a serous membrane lining the part of the common cavity of the body of terrestrial vertebrates, in which the lungs are enclosed (parietal sheet), and passing to the lungs (visceral sheet). A fully isolated pleural cavity is found in crocodiles, non winged turtles, monitor lizards, and birds. In mammals, the pleural (thoracic) cavities are completely delimited from the abdominal cavity by the diaphragm, and in the parietal layer, the diaphragmatic, costal, and
mediastinal part; The pleural cavity is filled with serous fluid
friction between the layers of the pleura during respiration.
