

A. ORAL CAVITY, BY E. KLEIN. 503 



the mucous membrane itself in a fan-like manner, or, more 

 rarely, to enter its transitional portion. 



The several muscular fibres, both of the muco-membranous 

 portion as well as of the cuticular portion, may be followed 

 into close proximity with the epithelium, or to the base of the 

 papillae. The sarcolemma is continued for a short distance 

 between the fibres of the membrana mucosa, or of the cutis, 

 in the form of delicate fibres. In the cutaneous portions the 

 muscular fibres partially decussate at the base of a hair fol- 

 licle, whilst elsewhere they may be followed on the wall of the 

 hair follicle to near the rete mucosum. 



This muscle in the lower lip is more strongly developed near 

 the middle line than at the sides; but in the upper lip, in which 

 it is usually more feebly marked, the opposite obtains. Laterally 

 the fibres are directed radially towards the oral opening, and 

 the area embraced by its origin and insertion is larger. 



At the angles of the mouth the mucous membrane rests upon 

 the inner surface of the buccinator, and extends, as the mucous 

 membrane of the cheeks, as far back as to the anterior border 

 of the vertical ramus of the lower jaw, without presenting any 

 important variation in its structure. Its epithelium is of the 

 same thickness and structure as that already described as 

 covering the muco-membranous portion, except that the number 

 of ribbed cells in the middle layers of the mucous membrane 

 of the cheeks is much greater than in that of the lips. 



The form of the papillae which project from the Memb. mucosa 

 into the epithelium is irregular ; they are often conical, with 

 elongated apices, or with their points prolonged in a filiform 

 manner. At their bases they are relatively broad. Their 

 height varies, sometimes amounting to half the depth of the 

 epithelium, sometimes scarcely exceeding its lower boundary 

 line. The Memb. mucosa is most dense beneath the epithelium, 

 and in it the same arrangement of the elements may be recog- 

 nised as in that of the lips. Towards the buccinator muscle it 

 becomes more loose. Its fasciculi stand in the same connection 

 with those of the subcutaneous tissue as in the case of the lips. 

 The glands of the mucous membrane of the cheeks (Glandulae 

 buccales) are thinly scattered, and are only to be found at con- 

 siderable distances from each other; near the point where 





