RESPIRATORY APPARATUS. 115 



3. The examination of the sinuses of the head is often 



of importance and should be made whenever a chronic nasal 

 discharge exists, especially when attended with an unilateral 

 bulging (enlargement) of the facial bones. Mere enlarge- 

 ments can be defined by palpation. The presence of exu- 

 dates in the sinuses can sometimes be determined by percus- 

 sion. The normal percussion sound of the sinuses is full, but 

 when they are filled with exudate or tumor masses, it becomes 

 flat. When the sinuses are only partially 

 filled the percussion sound is not changed. 

 Negative results from percussion, therefore, do not exclude 

 the presence of exudate. 



[A simple method of exploring the sinuses of the head, 

 to determine whether exudate (pus) is present in them or not, 

 is to bore a small hole into them with a "Yankee" drill. If the 

 sinuses contain pus or other exudate, the bit becomes soiled 

 by it and, if the contents are fetid, will smell.] 



V. The Submaxillary Lymph Glands. 



Although these glands do not properly belong to the 

 respiratory apparatus, the examination of them is significant 

 in the horse. In this animal especially, the glands become 

 sympathetically diseased when pathological conditions exist 

 within the domain of their lymph vessels. 



Anatomy. The lymph vessels from the nostrils to the ethmoid 

 bone carry their lymph to the submaxillary glands, a small glan- 

 dular packet as broad as and a little longer than a finger, lying 

 on each side of the intermaxillary space. They begin at the point 

 where the inferior maxillary artery passes under the ramus of the 

 lower jaw, and extend forward to the angle of the chin where 

 each unites with its fellow of the opposite side. Each lobule is 

 of about the size of a small bean. In horses of coarse conforma- 

 tion the intermaxillary space is often filled without the glands 

 being swollen. 



As soon as an absorption of irritant or 



infectious substances [bacteria] takes 



place in the region drained by the lymph 



