THE HEAD AND NECK 1253 



Development. — The soft palate is developed from a diflEerentiated portion 

 of the palatal shelf or plate of the majcillary process of either side. This 

 differentiated portion does not undergo ossification, but acquires muscular 

 tissue. Like the hard palate, the soft palate and the uvula are developed in 

 two symmetrical halves. 



The Tonsils. 



The tonsils {amygdalce) are two in number, right and left. Each 

 is situated in the triangular depression between the anterior and 

 posterior pillars of the fauces on either side, and, above it, is a small 

 recess, known as the supratonsillar fossa, which is the remains of the 

 inner portion of the second visceral cleft. The tonsil stands out as 

 an oval enlargement, covered by mucous membrane, and it lies 

 opposite the angle of the inferior maxilla, being under cover of it and 



I 



Lymphoid Follicle' ^""""**— — ^====^^^^^*^^ Buccal Epithelium 



Fig. 512. — Section through a Crypt of the Tonsil 



the adjacent portion of the ramus. The organ varies much in 

 size, but on an average it measures about i inch in length, about 

 f inch from before backwards, and about \ inch from within out- 

 wards. The internal surface is pitted with a number of orifices, 

 which lead into crypts in the interior. The outer surface, which 

 has a fibrous covering, is related to the superior constrictor of the 

 pharynx, some loose tissue intervening, and external to the superior 

 constrictor is the internal pterygoid muscle. Two of the tonsillar 

 arteries, namely, the tonsillar and inferior or ascending palatine, 

 lie between the superior constrictor and internal pterygoid. The 

 cervical portion of the facial artery in its course lies a little below 

 the outer aspect of the tonsil. The internal carotid artery is situated 

 about I inch from it on its outer and posterior aspect. 



Arteries. — ^These are as follows : (i) the tonsillar and inferior or 

 ascending palatine branches of the cervical portion of the facial ; 

 (2) the ascending pharyngeal branch from the external carotid; 

 •(3) the dorsalis linguae from the Ungual; and {4) the posterior and 

 external palatine offsets of the descending palatine artery from the 

 third part of the internal maxillary. 



