8 THE SURGICAL ANATOMY OF THE HORSE 



pressure to the groove near the base of the neck. This arrests the flow 

 of blood and causes the vein to become appreciably distended or 

 " raised." The observer should make himself quite accustomed to the 

 act of " raising " the vein, since it is not only necessary to do this in 

 performing the operation of phlebotomy, but also in all cases of examina- 

 tion for soundness. In the latter connection the vein is raised to ascer- 

 tain whether venesection has been performed on the animal, or to 

 discover whether the vessel is pervious. If venesection has been 

 previously performed there will be a dilatation at some part of the line 

 indicating the course of the " raised " vein. This dilatation indicates 

 the seat where the operation was performed. 



The hand should now be passed over the trachea, and the regularity 

 of the tracheal rings noted. Irregularity of this surface in the shape of 

 a depression or prominence may be indicative of the previous perform- 

 ance of the operation of tracheotomy. In this manner also fracture of 

 one or more of the tracheal rings due to accident may be diagnosed. 

 Upon arriving at the upper extremity of the trachea a rounded elevation 

 may be felt which indicates the position of the thyroid body. 



The inclination of the oesophagus to the left side near the root of 

 the neck may be observed during the passage of a bolus of food along 

 the tube. 



