104 THE AXATOMV OK TUE HORSE. 



smooth and convex, and in health it is closely applied to the chest-wall. 

 The intei'nal (or mediastinal) surface is moulded on the mediastinum 

 and the organs contained in it. Thus, it presents opposite the heart 

 a dejiression for the lodgment of that organ ; behind that point, and 

 near the uj)per limit of tlie surface, a longitudinal groove for the posterior 

 aorta ; and beneath that again a second furrow parallel to the fii-st but 

 not so deep, which is the impress left 1)y the oisophagus. This last 

 impression is very faint on the right lung. This surface also presents 

 the root of the lung, which is situated close behind and above the 

 depression for the heart ; and the broad lif/ament of the lung (or ligamen- 

 tum latum 2)idnionis) already mentioned. In front of the heart, where 

 this surface is applied to the anterior mediastimim, it is narrow and flat. 

 The inner surface of the right lung presents posteriorly a small, semi- 

 detached lobule, not present on the left. The base (or diajyhragmatic 

 surface) is concave and moulded on the diaphragm. This surface on the 

 right lung shows the base of the small, semi-detached lobule, and the 

 posterior vena cava disappearing into the fissure between that lobule 

 and the main mass of the lung. The apex of the lung is pointed, and 

 lies at the entrance to the chest. The sujyerior (or vertebral) border is 

 long, thick, and roimded, and it is lodged in the costo-vertebral groove 

 at the roof of the cavity. The infei-ior (or sternal) border is short and 

 sharp; and opposite the heart it is widely notched, a circumstance 

 which allows the pericardium to be tapped at this point without danger 

 of wounding the lung. The notch is smaller on the right side. The 

 posterior (or diaphragmatic) border circumscribes the base, and the greater 

 part of it is included between the periphery of the diaphragm and the 

 chest-wall. 



Directions. — The student should now attempt by the following method 

 to restore the lung as nearly as possible to its natural dimensions 

 and relations. The nozzle of a pair of bellows should be wrapped 

 firmly round with a strip of wet cloth until it is made of a convenient 

 size to fit the trachea, which is to be cut across about the middle of the 

 neck for its reception. The nozzle is then to be tied tightly into the 

 trachea with a thick piece of string cai-ried several times round, and the 

 lung is to be gradually inflated while an assistant guides it into position, 

 and guards it from being wounded by the cut ends of the ribs. Provided 

 the lung has not been injured, it can by this means be restored to its 

 natural position, and the student should then observe the area of 

 pericardium which is left uncovered at the notch in the -lower border. 

 The right side of the chest may next be opened, making the same 

 incisions as on the left. On raising the base of the right lung from 

 the diaphragm, its supernumerary lobule will be seen, and also the 

 posterior vena cava and right phrenic nei-ve invested by the special fold 

 of pleura. The right lung may then be inflated, and the extent of 



