THE TRACHEA -jj 



attached to its performance provided due care and dexterity are shown 

 during the insertion of the tube. That part directed towards the lungs 

 should be inserted first. 



By a reference to Plate XVI. it will be seen that there are no important 

 vessels or nerves near the usual seat, consequently the operator's attention 

 can be wholly directed to the prevention of hsemorrhage from the 

 cutaneous and muscular vessels, and the removal of the sections of 

 cartilage. The operation is best performed whilst the animal is in the 

 standing position, and since it is not very painful and the time taken is 

 quite brief (only a few minutes) only local anesthesia is necessary. 



When it is necessary to adopt a seat near the root of the neck, the 

 'ugular vein and carotid artery should be located in order that injury to 

 them may be avoided. 



Similarly, when for some pathological or other reason it is necessary to 

 select a seat in the upper part of the neck, it will be well to remember 

 that occasionally in horses, there is present the isthmus connecting the 

 two thyroid bodies across the inferior face of the trachea, as is found in 

 man. This, if present, will be avoided if the seat of operation selected 

 is below the fourth tracheal ring. 



THE GUTTURAL POUCHES 



There are two of these, placed one on either side the median sagittal 

 line. Each is a large sac which extends from near the atlanto-axial joint 

 to near the upper extremity of the posterior nares. The pouches meet 

 one another on the middle line where their mucous linings come into 

 apposition. 



Various structures are related to their outer aspect, the stylo- 

 maxillaris, the digastricus (upper belly), the stylo-hyoid, and the occipito- 

 styloid muscles lie over the pouch, which is crossed by the occipital and 

 both the external and internal carotid arteries. Behind the styloid cornu 

 of the hyoid bone, in addition to the foregoing, the pouch is crossed by 



