THE ORAL CAVITY. 57 



In the posterior portion of the oral cavity may be seen the soft palate with the uvula, the 

 potato- glossal and palato-pharyngeal arches, and, between the latter structures, the more or less 

 prominent faucial tonsil, which is frequently the seat .of simple or diphtheric inflammation. Both 

 the soft and the hard palates receive their blood from the terminal branches of the descending 

 palatine artery, which is given off from the internal maxillary in the spheno-maxillary fossa, passes 

 downward through the posterior palatine canal, and makes its exit at the posterior palatine fora- 

 men. [In repairing cleft palate it is necessary, in order to avoid hemorrhage and to maintain the 

 nutrition of the flaps, to preserve these vessels. The incision is therefore made close to the 

 alveolar borders outside the vessels. ED.] Other branches of the posterior palatine artery pass 

 through the accessory palatine canals. The posterior and accessory palatine canals also trans- 

 mit the descending or palatine branches (anterior, middle, and posterior) of the spheno-palatine 

 ganglion. 



The normal tonsil (see Fig. 20 and Plate 4) projects but slightly, if at all, above the level of 

 the surrounding mucous membrane, and, as it is situated in the niche between the palatine 

 arches, it is visible to a different degree in different subjects. The surface of the tonsil is dotted 

 by the apertures of numerous crypts. In consequence of its great tendency to become inflamed 

 and swollen, its relation to the isthmus of the fauces is particularly important. The swelling leads 

 not only to dysphagia, the tonsils sometimes meeting in the median line, but also to a more or less 

 marked constitutional depression. It is clear that diseases of the tonsils may extend along the 

 upper surface of the soft palate to the choanae (posterior nares) and to the Eustachian tubes, and 

 downward into the pharynx and larynx. The operation of tonsillotomy, so frequently performed 

 upon children, is often followed by active hemorrhage which may be difficult to arrest. This is 

 due to the tonsillar branch of the ascending palatine artery (from the facial), or, if the incision has 

 penetrated very deeply, to the trunk of the ascending palatine itself. Occasionally a particularly 

 severe hemorrhage is observed, in which case the "slashing" operator may not only have removed 

 the tonsil but also the styloglossus and stylopharyngeus muscles and lacerated the facial artery, 

 which is separated from the tonsil by these muscles. The internal carotid artery is quite dis- 

 tant and is not endangered in tonsillotomy, although fatal hemorrhage has been observed as 

 the result of a tonsillar abscess ulcerating into this vessel. 



The pharynx is situated behind the oral cavity and passes into the neck without any sharp 

 line of demarcation. If the pharynx is incised posteriorly, it will be seen to have a threefold 

 communication. The upper portion, attached to the base of the skull, opens anteriorly into 

 the nasal fossas through the choanae, and is known as the pars nasalis pharyngis (naso- pharynx). 

 Its lower boundary is formed by the soft palate, which is in apposition with the dorsal wall of the 

 pharynx during deglutition, and so divides the pars nasalis from the middle portion of the pharynx, 

 the pars oralis. The orifice of the Eustachian tube is found in the pars nasalis directly behind the 

 jsterior extremity of the inferior turbinated bone (see page 53 and Fig. 19). It is bounded 

 posteriorly by the torus tubarius (Eustachian cushion), the prominence due to the trumpet- 

 shaped end of the Eustachian tube, from which point the salpingo-pharyngeal fold (see Fig. 19 

 and Plate 4) may be seen running downward. The pocket-like fossa of Rosenmuller, or pharyn- 



recess, is situated behind the torus tubarius, and nearer the median line may be seen the 

 pharyngeal tonsil, which varies in size in different individuals and extends into the fossa of 



