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 



TV. 



Seventh rib — j- 



Sixth rib 



Left vagus nerve — 



Fifth rib — 

 Left phrenic nerve 



Fourth rib 



Internal thoracic vessels 



\ ^J^xr-' Sympathetic trunk 



Vena azygos 



Thoracic duct 

 (Esophagus 

 Right vagus nerve 



Right phrenic nerve 

 Pericardiac pleura 



Sternum 



Fig. 359. — Cross-section of Thorax ok New-born Foal. 

 A, Aorta; Br., bronchi; P.A., pulmonary arteries; /, lymph gland; «..!., right atrium; L.A., left atrium; R.V .. 



right ventricle; />.!'., 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 six^cial sagittal fold (Plica vense cava?) 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 vense cavse, and intervenes between 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 contmuous whole. 



