THE SOFT PALATE AND TONSIL. 49 



two semilunar margins, the edges of which pass down- 

 wards to the sides of the tongue, united in a central raphe, 

 from which depends a prolongation, the uvula. 



In structure the soft palate consists anteriorly and in- 

 feriorly of a mucous membrane, thickly studded with 

 muciparous glands, continuous with that of the posterior 

 region of the mouth, and posteriorly and superiorly of a 

 second membrane, continuous with that of the naso- 

 pharyngeal region. Between these mucous layers is a 

 musculo-tendinous one, consisting of portions of the fol- 

 lowing pairs of intrinsic muscles, the levatores palati 

 and the tensores or circumflexi palati ; and of extrinsic 

 muscles, the palato-glossi and the palato-pharyngei. 

 Some delicate muscular fibres are to be found in the 

 uvula. The order in which the structures enter into the 

 formation of the velum is as follows : From before back- 

 wards, (1) the anterior layer of mucous membrane ; (2) the 

 aponeurosis of the tensores palati, with which is blended 

 the attachments of the palato-glossi and palato-pharyngei ; 

 (3) the levatores palati, uniting in the median raphe ; (4) 

 the posterior layer of mucous membrane. 



The pillars of the fauces are formed by the divergence 

 of the palato-glossus and palato-pharyngeus, and include 

 a triangular interval, the base being downwards, in which 

 is situated the tonsil. The posterior pillars formed by 

 the palato-pharyngei are nearer each other than the 

 anterior, formed by the palato-glossi. 



The space between the palatine arches of both sides is 

 called the isthmus of the fauces, and is bounded above by 

 the free margin of the palate, below by the dorsum of 

 the tongue, and laterally by the pillars of the fauces and 

 tonsils. 



A correct knowledge of the attachments and actions 



