282 HEAD AND NECK 



wards and backwards from the sides of the lower margin of 

 the soft palate, and each encloses a pharyngo-palatine muscle. 

 In the triangular interval which is formed by the divergence 

 of the glosso- and pharyngo-palatine arches, on each side, lies 

 a palatine tonsil. 



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

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

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



Pharynx. The pharynx is a wide musculo-aponeurotic 

 canal, about 12.5 cm. (5 inches) long. It extends from the 

 base of the cranium to the level of the body of the sixth 

 cervical vertebra (Fig. 1 10). There, at the lower border of the 

 cricoid cartilage, it becomes continuous with the oesophagus. 

 It is placed posterior to the nasal cavities, the mouth and the 

 larynx, and 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 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 

 (Fig. 112). 



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 above, through the mouth, or from below, through 

 the oesophagus. 



When the pharynx is distended it has a somewhat ovoid 

 form. Posteriorly, its wall is complete, and, when in position, 

 it lies anterior to the upper six cervical vertebrae, the pre- 

 vertebral muscles, and the prevertebral fascia. It is bound 

 to the prevertebral fascia by some lax connective tissue which 

 offers no impediment to the movements of the canal during 

 the process of deglutition. On each side, the pharynx is 

 related to the great vessels and nerves of the neck, as well 



