Veterinary Splanchnology and Applied Anotomy

PLEURAE

• The pleurae are serous membranes, which enclose on each side a pleural cavity. These line the walls of the thorax from the lateral laminae of the mediastinum, and then reflected from the latter upon the surface of the lungs. Thus we distinguish parietal, mediastinal and pulmonary or visceral parts of pleura
• The parietal pleura line the thoracic walls. On the lateral thoracic wall it is adherent to ribs and intercostal muscles and is termed the costal pleura
• Behind it is closely attached to diaphragm, forming the diaphragmatic pleura
• The mediastinal pleura cover the organs in the mediastinal space and are in part in opposition with the opposite sac
• The part which is adherent to the pericardium is the pericardiac pleura. From the mediastinum, each pleura is reflected on the corresponding lung forming the pleura pulmonalis or the visceral pleura. The reflection occurs around and behind the hilus of the lung
• Caudal to the root of the each lung, there is a horizontal fold of pleura called the pulmonary segment
• The right pleura forms a special sagittal fold, which encloses the caudal vena cava in its upper edge; it is therefore called the fold of the vena cava (Plica venacava)
• It gives off a small accessory fold for the right phrenic nerve
• The pleural cavity contains a film of clear serous fluid, the liquor pleurae
• The cavity is normally a capillary space
• The pleura resemble the peritoneum in structure and appearance
• It is attached to the structures that it covers by a subserous tissue called endothoracic fascia
• The cupola pleurae or apex of each pleural sac lies at the thoracic inlet
• The right cupola projects beyond the cranial border of the first rib under the scalenus. The left cupola usually does not extend beyond the plane of first rib