560 HARD PALATE. SOFT PALATE. 



The Mouth is the irregular cavity which contains the organs of 

 taste and the principal instruments of mastication. It is bounded in 

 front by the lips ; on either side by the internal surface of the cheeks ; 

 above by the hard palate and teeth of the upper jaw ; below by the 

 tongue, by the mucous membrane stretched between the arch of the 

 lower jaw and the under surface of the tongue, and by the teeth of 

 the inferior maxilla ; and behind by the soft palate and fauces. 



The Lips are two fleshy folds formed externally by common integu- 

 ment, and internally by mucous membrane, and containing between 

 these two layers the muscles of the lips, a quantity of fat, and numer- 

 ous small labial glands. They are attached to the surface of the upper 

 and lower jaw, and each lip is connected to the gum in the middle 

 line by a fold of mucous membrane, the fraenum labii superioris and 

 fraenum labii inferioris, the former being the larger. 



The Cheeks (buccse) are continuous on either hand with the lips, and 

 form the sides of the face ; they are composed of integument, a large 

 quantity of fat, muscles, mucous membrane, and buccal glands. 



The mucous membrane lining the cheeks is reflected above and 

 below upon the sides of the jaws, and is attached posteriorly to the 

 anterior margin of the ramus of the lower jaw. At about its middle, 

 opposite the second molar tooth of the upper jaw, is a papilla, upon 

 which may be observed a small opening, the aperture of the duct of 

 the parotid gland. 



The Hard palate is a dense structure, composed of mucous membrane, 

 palatal glands, fibrous tissue, vessels, and nerves, and firmly connected 

 to the palate processes of the superior maxillary and palate bones. It 

 is bounded in front and on each side by the alveolar processes and 

 gums, and is continuous behind with the soft palate. Along the 

 middle line it is marked by an elevated raphe, and presents upon each 

 side of the raphe a number of transverse ridges and grooves. Near 

 its anterior extremity, and immediately behind the middle incisor 

 teeth, is a papilla which corresponds with the termination of the naso- 

 palatine canal, and has been supposed to be endowed with a peculiar 

 sensibility. 



The Gums are composed of a thick and dense mucous membrane, 

 which is closely adherent to the periosteum of the alveolar processes, 

 and embraces the necks of the teeth. They are remarkable for their 

 hardness and insensibility; and for their close contact, without ad- 

 hesion, to the surface of the tooth. Flora the neck of the tooth they 

 are reflected into the alveolus, and become continuous with the peri- 

 osteal membrane of that cavity. 



The Tongue has been already described as an organ of sense ; it is 

 invested by mucous membrane, which is reflected from its under part 

 upon the inner surface of the lower jaw, and constitutes, with the 

 muscles beneath, the floor of the mouth. Upon the under surface of 

 the tongue, near its anterior part, the mucous membrane forms a con- 

 siderable fold, which is called the frumum linguae ; and on each side 

 of the fraenum is a large papilla, the commencement of the duct of the 



