THE MOUTH. . 1111 



in the centre by the conical projection of varying size, called the uvula, which hangs 

 down from its inferior margin. Laterally the soft palate is intimately connected on 

 each side with two prominent folds, called the palatine arches. The exact relation- 

 ship of the soft palate to these is as follows. The free posterior margin of the soft 

 palate passes into the pharyngo-palatine arch (O.T. posterior pillar of the fauces), 

 which passes downwards for some distance on the side wall of the pharynx. 



The glosso-palatine arch (O.T. anterior pillar of the fauces), on the other hand, 

 passes below into the side of the tongue. Traced upwards, it runs on to the 

 inferior surface of the soft palate, and is continuous with the margin of the uvula. 



The two palatine arches on each side are 7-8 mm. apart, and on the side wall, 

 between each pair, there is a fossa or depression which is occupied in part by the 

 palatine tonsil. This region belongs properly to the pharynx, and will be described 

 in detail when that part is dealt with, but at the present stage the relation of this 

 fossa of the tonsil to the soft palate should be carefully noticed. 



The superior surface of the soft palate forms a continuation backwards and 

 downwards of the floor of the nasal cavity, and constitutes the floor of the nasal 

 part of the pharynx. It is covered by a prolongation of the nasal mucous membrane, 

 partly ciliated in character. The inferior surface is arched, and forms the backward 

 prolongation of the roof of the mouth. 



In the foetus the whole of the epithelial covering of the soft palate is ciliated, but after birth 

 the ciliated epithelium is largely replaced by stratified squamous epithelium, except at the 

 . margin of the palate. 



Structure. The framework of the soft palate is formed of a strong fibrous sheet, called the 

 palatine aponeurosis. To it several muscles are attached. These structures, together with fibrous 

 tissue, gland- vessels, and nerves, are covered by mucous membrane on each surface. 



The palatine aponeurosis, which is confined to the anterior part of the soft palate, is in the 

 form of a thin flat sheet, constituting a common tendon for the palatine muscles which are 

 attached to (or blended with) its posterior margin. Its anterior margin is united to the posterior 

 edge of the horizontal parts of the palatine bones. With the exception of the aponeurosis of the 

 tensor veli palatini which passes into its lateral part, the muscles do not, as a rule, reach 

 further forwards than to within 8 or 10 mm. of the posterior edge of the hard palate. 



The muscles entering into the formation of the soft palate are the mm. 

 pharyngo-palatini, uvulae, levatores veli palatini, tensores veli palatini, and glosso- 

 palatini. For the details of the attachments and arrangement of these muscles, 

 see p. 466. 



The anterior part of the soft palate for 8 or 10 mm. (J in.) contains practically no 



, muscular fibres ; it is composed of the palatine aponeurosis, covered by an extremely 



, thick layer of glands on the inferior surface and by mucous membrane on both surfaces. 



This anterior portion is much less movable than the rest of the soft palate, and forms a 



relatively horizontal continuation backwards of the hard palate, stretching across between 



the two medial pterygoid laminae. It is upon this portion chiefly that the tensor veli 



palatini muscles act. The posterior and larger part contains muscular fibres in abundance, 



slopes strongly downwards, and is freely movable, being the portion upon which the 



remaining palatine muscles act. 



The mucous membrane of the inferior surface of the palate, which is covered by stratified 

 squamous epithelium, is firmer and more closely adherent in front, near the rugae, than behind, 

 . near the soft palate. 



Mucous glands, the orifices of which can be seen as dots with the naked eye, are extremely 

 abundant in the soft palate, and in the posterior half of the hard palate, except near the raphe. 

 They are wanting in the anterior part of the palate, where the mucous membrane is particularly 

 dense. 



The plicae palatinse (which correspond to more strongly developed ridges in carnivora, etc.) are 

 very well marked in the child at birth, although, perhaps, relatively less distinct in the foetus of 

 five or six months ; in old age they become more or less obliterated and irregular. At birth, 

 also, and in the foetus, the incisive pad at the anterior end of the raphe is continued over the 

 edge of the gum into the frenulum of the upper lip. 



The uvula, already referred to, is a conical projection, very variable in length, which is con- 

 tinued downwards and backwards from the middle of the posterior border of the soft palate. It 

 is composed chiefly of a mass of racemose glands and connective tissue covered by mucous mem- 

 brane, and containing a slender prolongation of the uvular muscle in its upper part. 



The vessels oi' the palate are : 



(1) Branches from the descending palatine artery, a branch of the internal maxillary artery. 



Of these, some small vessels, the lesser palatine arteries, emerge from the foramina palatina 



71 c 



