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DISSECTION OF THE PHARYNX. 



Vestibule. 



Lining of 

 the mouth 



differs in 

 parts : 



on roof, 



floor, 



cheek, and 

 lips. 



Papillae. 



Cheek ; 

 extent, 



and struc- 

 ture. 



Lips, 



formed by 

 orbicularis, 



contain 

 arteries. 



Teeth ; 

 number and 

 arrangement 

 in jaw. 



molar tooth in the upper jaw, is the opening of the parotid duct. 

 The anterior opening of the mouth is bounded by the lips ; and the 

 posterior is the isthmus faucium, leading into the pharynx. The 

 space between the lips and the teeth is distinguished from the rest 

 of the cavity as the vestibule of the mouth. 



The mucous membrane is less sensitive on the hard than on the soft 

 boundaries of the mouth ; it lines the interior of the cavity, and 

 is reflected over the tongue. In front it is continuous with the skin, 

 and behind with the lining of the pharynx. The epithelium cover- 

 ing the membrane is scaly and stratified. 



Between each lip and the front of the corresponding jaw the 

 membrane forms a small fold frsenulum. Over the bony part of 

 the roof it blends with the dense tissue enclosing the vessels and 

 nerves ; on the soft palate it is smooth, and thinner. Along the 

 middle of the roof is a slightly raised raphe, which ends in front 

 opposite the anterior palatine fossa in a small papilla ; and on each 

 side of this, at the fore part of the hard palate, there are two or 

 three irregular transverse ridges. In the floor of the mouth the 

 membrane forms the frsenum linguae beneath the tip of the tongue, 

 and on each side of the frseimm it is raised into a ridge by the sub- 

 lingual gland, at the fore part of which is a small papilla, perforated 

 by the opening of Wharton's duct. On the interior of the cheek 

 and lips the mucous lining is smooth, and is separated from the 

 muscles by small buccal and labial glands. 



Over the whole cavity, but especially on the lips and tongue, are 

 papilla. 



The CHEEK extends from the commissure of the lips to the ramus 

 of the lower jaw, and is attached above and below to the alveolar 

 process of the jaw on the outer aspect. The chief constituent of the 

 cheek is the fleshy buccinator muscle : on the inner surface of this 

 is the mucous membrane ; and on the outer the integuments, with 

 some muscles, vessels, and nerves. The parotid duct perforates the 

 cheek obliquely opposite the second molar tooth of the upper jaw. 



The LIPS surround the opening of the mouth ; they are formed 

 mainly by the orbicularis oris muscle covered externally by integu- 

 ment and internally by mucous membrane. The lower lip is the 

 larger and more moveable of the two. Between the muscular struc- 

 ture and the mucous covering lie the labial glands ; and in the sub- 

 stance of each lip, internal to the muscular structure, and separated 

 from the free edge by the marginal bundle of the orbicularis, is 

 placed the arch of the coronary arteries. 



TEETH. In the adult there are sixteen teeth in each jaw, which are 

 set in the alveolar borders in the form of an arch, and are surrounded 

 by the gums. Each dental arch has its convexity turned forwards ; 

 and, commonly, the arch in the maxilla overhangs that in the man- 

 dible when the jaws are in contact. The teeth are similar in the 

 half of each jaw, and have received the following names : the 

 most anterior two are incisors, and the one next behind is the canine 

 tooth ; two, still farther back, are the two bicuspids ; and the last 



