548 



RESPIKATORY SYSTEM OF THE DOG 



anterior to the fissure represents the apical and cardiac lobes, which are, however, 

 separated only Idv the cardiac notch, not by an interlobar fissure, as is usual in the 



Trachea 



Dorsal border 



Cardiac lobe Intermediate lobe 



Fig. 487. — Right Lung op Pig; AIedial View. 



1, Left bronchus (cut off) ; 2, 2, pulmonary arteries; 5, 5, 3, pulmonary veins; 4. posterior vena cava; 5, groove for 



anterior vena cava; 6, groove for vena azygos; 7, groove for aorta; 8 (placed on groove for oesophagus), lines of pleural 



reflection. Arrows indicate interlobar fissures. 



/ 



right lung. The lobulation is distinct, but the interlobular septa are thinner than 

 in the ox. 



THE THYROID GLAND 



The thjTroid gland is large and is situated usually at a considerable distance 

 from the larynx, but may be in contact with it. The lateral lobes are irregularly 

 triangular in outline, and are two inches or more (ca. 5-6 cm.) in length in a large 

 adult. They are united to a considerable extent ventrally, so that an isthmus 

 cannot be distinguished. The gland is related deeply to the sides and ventral face 

 of the trachea, and is in contact dorsally with the oesophagus. The chief artery 

 enters at the posterior extremity. 



THE THYMUS 



The thymus in young subjects is very large, extending to the larynx or even to 

 the mandibular space. 



RESPIRATORY SYSTEM OF THE DOG 



THE NASAL CAVITY 



The nostrils are situated on the muzzle, with which the upper lip blends. They 

 are shaped somewhat like a comma, with the broad part next to the septum and 

 the narrow part directed backward and outward. The skin around the nostrils 

 is bare, usually black, and in health moist and cool. The muzzle is marked by a 

 median furrow (philtrum), or a deep fissure in some breeds. The cartilaginous 



