RESPIRATION. 43 



The thyroid cartilage (shield like J is located at the upper 

 and front portion of the larynx extending well around on the 

 sides. 



The arytenoids are two in number, one on each side. The 

 two taken together are shaped somewhat like the front part of 

 a pitcher, situated at the sides of the upper part of the larynx 

 coming together at the median line. These cartilages give at- 

 tachments to the vocal cords. 



The cricoid is shaped like a ring with a process on the up- 

 per and front part, which causes this cartilage to resemble a 

 seal ring. It is located at the lower portion of the larynx and 

 connected with the trachea. 



The vocal cords are a pair of narrow fibrous bands so situ- 

 ated as to include a narrow triangular space betwen them. They 

 are attached in front to the thyroid and behind to the arytenoids. 



Trachea, or wind pipe. — This is located beneath and in front 

 of the aesophagus. It is a long tube composed of about 50 car- 

 tilage rings beginning at the cricoid cartilage above and terminates 

 at the bronchi below. It therefore connects the larynx and bron- 

 chi. It is lined by a mucous membrane which is covered by 

 ciliated cells. 



Bronchi. — Are two in number, are branches of the trachea 

 and very similar to it in structure and function. One bronchus 

 attaches to the root of each lung. 



Lungs. — There are two, right and left. These are the es- 

 sential organs of respiration, and located in thoracic cavity. Each 

 lung is cone-shaped- and enclosed in a separate pleural sack ( ex- 

 plained ) , and the other layer of the pleura lines the interior of 

 the thorax. In the lungs of a horse the lobes are not distinctly 

 marked. Some authors make no definite divisions ; others de- 

 scribe the right lung as having three lobes and the left, two. 

 The lobes are then described as anterior, middle, and posterior, 

 the left lung in the horse having no middle lobe. 



In the cow's lungs the lobes are distinctly marked. The 

 left lung has three distinct lobes. The right lung has four lobes 

 by reason of the anterior lobe being divided into two parts : first 

 and second. 



The root is where bronchi and large vessels attach to each 



lung. 



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