SECTION VIII 

 THE RESPIRATORY ORGANS 



THE Organs of Respiration are the lungs and trachea, the 

 latter being the passage by means of which air is carried from 

 the pharynx to the lungs. 



Breathing consists of the acts of inspiration and expiration; 

 in the former, air is drawn into the pharynx through either the 

 nose or mouth and conveyed by means of the trachea to the 

 lungs ; the air is expelled in the same way. 



The upper part of the air passage, the larynx, is specially 

 modified by cartilages and muscles to produce sounds i.e., the 

 voice during expiration. 



The Pharynx is a large space behind the nose and mouth in 

 the lower part of which are the openings of the larynx and 

 oesophagus ; the pharynx is compressed laterally, and its anterior 

 wall is practically non-existent, the lateral walls being attached 

 to the sides of the nasal, buccal and laryngeal orifices. The 

 posterior wall is attached by areolar tissue to the muscles in 

 front of the first six cervical vertebrae, and above, it is attached 

 to the basilar process of the occipital bone and to the temporal 

 bones. 



The upper part of the pharynx is almost separated off from 

 the lower part by the soft palate, which projects backwards from 

 the palatal processes of the maxillary bones, and in this upper 

 part is found the orifices of the Bustachian tube and the pharyn- 

 geal tonsil. Below the soft palate is the tonsil on each side. 

 Below this the pharynx rapidly narrows as it passss the opening 

 of the larynx and becomes the oesophagus. 



The Larynx is the upper part of the air passage, and is placed 

 in front of the fourth, fifth, and sixth cervical vertebrae. It con- 



131 



