ORGANS OF VOICE AND RESPIRATION 211 



The nerves are the superior laryngeal, the inferior or 

 recurrent laryngeal, and branches of the sympathetic of 

 each side. 



THE TRACHEA. 



The trachea extends from the lower border of the larynx 

 (opposite the lower border of 5th cervical vertebra) to 

 the level of the disc between the 4th and 5th dorsal vertebrae, 

 there dividing into the two bronchi. In length it measures 

 4^ inches. 



Relations in the Neck. 



In front. 

 Skin. 



Superficial and deep fasciae. 

 Anastomosis of anterior 

 jugular veins. 



Isthmus of thyroid gland. 

 Inferior thyroid veins. 



Laterally. 



Cervical fascia. 



Common carotid 

 artery. 



Lateral lobe of 

 thyroid gland. 



Inferior thyroid 

 artery. 



Recurrent laryn- 

 geal nerve. 



Behind. 

 QEsophagrs. 



In the Thorax. 



In Front. Right Side. 



Manubrium Right pneumo- 

 sterni. gastric nerve. 



Innominate ar- 



tery. 

 Pleura. 



Left Side. 

 Left cardiac nerves. 

 Left pneumogastric 



nerve. 

 Left recurrent 



laryngeal nerve. 

 Aortic arch. 

 Left subclavian m- 



tery. 

 Pleura. 



Posteriorly. 



(Esophagus. 



Origin of sterno 



mastoid. 

 Origins of sterno- 



t hy roid and 



sterno-hyoid. 

 Remains of thymus 



gland. 

 Left innominate 



vein. 

 Commencements of 



innominate and 



left carotid ar- 

 teries. 



Arch of aorta. 

 Deep cardiac 



plexus. 



The cartilages, from sixteen to twenty in number, are 

 U-shaped, the anterior or convex part being cartilage, the 

 posterior j fibrous membrane. 



142 



