452 



RESPIRATORY SYSTEM OF THE HORSE 



where this layer is adherent to the pericardium, it is distinguished as pericardiac 

 pleura (Pleura pericardiaca)/ 



The pleura is reflected at the root of the lung, which it covers, constituting 

 the visceral or pulmonary pleura (Pleura pulmonalis). Behind the root of the 

 lung a considerable triangular area is not covered by the pleura, the two lungs being 

 attached to each other by connective tissue in this situation. 



The ligament of the lung (Lig. pulmonale) is a fold formed by the reflection 

 of the pleura from the mediastinum and the diaphragm to the lung, behind the 



Seventh rib 

 Sixth rib- 



Left vagus nerve — 



Fifth rib 

 Left 'phrenic nerve 







Fourtii rib 



Internal thoracic vessels 



Sympathetic trunk 



Vena czygos 



Thoracic duct 

 Oesophagus 

 Right vagus nerve 



Right phrenic nerve 



Pericardiac pleura 



Sternum 



/ 



Fig. 359. — Cross-section of Thor.^x of Nkw-bor.v Fo.\l. 

 .4, Aorta; i?r., bronchi; P. . 1 ., pulmonary arteries; /, lymph gland; i?..l ., risht atrium; L.. 4., left atrium; R.V., 



right ventricle; L.V., left ventricle of heart. 



triangular area of adhesion just mentioned. It is seen when the base of the lung 

 is drawn outward. It contains elastic tissue, especially in its posterior part. 



The right pleura forms a special sagittal fold (Plica vense cavse) about a 

 handbreadth to the right of the median plane, which incloses the posterior vena 

 cava in its upper edge and gives off a small accessory fold for the right phrenic 

 nerve. The fold arises from the thoracic floor and from the diaphragm below the 

 foramen venae cava?, and intervenes l)etween the mediastinal lobe and the body of 

 the right lung. It is delicate and lace-like. 



1 The student should bear in mind that these terms are employed simply as a matter of 

 convenience in description; all the parts, though differently named, form a continuous whole. 



