PHARYNX 369 



palatinus muscle. The arcus pharyngopalatinns, more strongly 

 marked, inclines posteriorly, and is lost upon the side of the 

 pharynx ; it encloses the pharyngo-palatinus muscle. 



In the triangular interval which is formed by the divergence 

 of these two folds lies the tonsil. 



Strictly speaking, the term isthmus faucium should be confined to the 

 interval between the two glosso-palatine arches, as the tonsil and the 

 pharyngo-palatine arches belong to the lateral wall of the pharynx. 



Pharynx. The pharynx is a wide musculo-aponeurotic 

 canal, about 5 inches lona( which extends from the base of 

 the cranium to the level of the body of the sixth cervical 

 vertebra./' There, at the lower border of the cricoid cartilage, 

 it becomes continuous with the oesophagus. Placed posterior 

 to the nasal cavities, the mouth and the larynx, it serves as 

 the passage which conducts air to and from the larynx, as well 

 as the food from the mouth to the oesophagus. 



Under ordinary conditions it is expanded from side to 

 side and compressed antero-posteriorly, so that it possesses 

 anterior and posterior walls and two lateral borders. Above the 

 level of the orifice of the larynx there is always sufficient 

 space for the passage of air to the lungs, but below the 

 orifice of the larynx the anterior and posterior walls are in 

 contact, except when separated by the passage of food. 



It is widest above, at the base of the cranium, posterior 

 to the orifices of the auditory tubes (O.T. Eustachian). 

 Thence it narrows to the level of the hyoid bone. It widens 

 again at the level of the upper part of the larynx and then 

 rapidly narrows to its termination. 



To obtain a proper idea of the connections of the pharynx, the dissector 

 should distend its walls moderately by stuffing it with tow. This may be 

 introduced either from aboye, through the mouth, or from below, through 

 the oesophagus. 



The pharynx will now present a somewhat ovoid form. 

 Posteriorly, its wall is complete, and, when in position, it lies 

 anterior to the upper six cervical vertebrae, the prevertebral 

 muscles, and the prevertebral fascia. To these it is bound 

 by some lax connective tissue which offers no impediment to 

 the movements of the canal during the process of degluti- 

 tion. Laterally, the pharynx is related to the great vessels 

 and nerves of the neck, as well as to the styloid process and 

 the muscles which take origin from it. Upon this aspect of 



VOL. II 24 



