PHARYNX. 



9.51 



under surface by a dense and thick mucous 

 membrane: numerous glands with vessels and 

 nerves also enter into its structure. The mu- 

 cous membrane covering the bony palate with 

 that forming the gums is of a paler colour than 

 elsewhere in the interior of the mouth, and is 

 united by a remarkably condensed and thick 

 submucous areolar tissue to the periosteum, 

 especially in the mesial line, where the two 

 structures appear blended : on either side the 

 union occurs by fibrous prolongations, allowing 

 a thick layer of glands and the vessels and 

 nerves of the palate to intervene : the mem- 

 brane has a thick investment of epithelial 

 scales, and is capable of resisting considerable 

 pressure ; of greater thickness before than be- 

 hind, indifferently sensible, and in structure 

 bears some analogy to that of the skin : the 

 glands in every way resemble those of the 

 cheeks and lips, and open in like manner upon 

 the mucous surface ; two larger openings than 

 the rest may often be seen on either side the 

 median line towards the back part of the 

 palate. 



The gums (Gr. ou^a, Lat. gingiva;) resemble 

 in colour and structure the palatine membrane, 

 except that the glandular apparatus is here re- 

 duced to mere follicular pores. They cover 

 either surface of the alveolar processes of the 

 jaws, intimately connected with the periosteum, 

 and extend a little way beyond the alveoli to 

 rest against the necks of the teeth by a festooned 

 edge. The denticulated processes of this edge 

 are continued across the alveoli between the 

 teeth, by which means the gums on either sur- 

 face communicate with each other; between 

 these processes the concave margin of the gum 

 is reflected upon itself to enter the alveoli, 

 lining their inner surface, and closely applied 

 to the fangs of the teeth. (See TEETH.) The 

 palate and gums receive their arterial branches 

 from the internal maxillary and facial arteries, 

 and their nerves from the spheno-palatine or 

 Meckel's ganglion. (See FIFTH PAIR OF 

 NERVES.) The palatine nerves gain the palate 

 through the anterior and posterior palatine fora- 

 mina, and course along immediately beneath 

 the periosteum, lodged in grooves, together with 

 the accompanying arteries, upon the inferior 

 surface of the palatine processes of the superior 

 maxillary and palate bone. The palatine arch 

 constitutes the septum between the nasal and 

 buccal cavities, and forms the fixed and resist- 

 ing surface against which the tongue acts in 

 deglutition and in the articulation of certain 

 sounds ; previous to the irruption of the teeth 

 and after their decay, the gums are continued 

 over the alveolar processes, and by their almost 

 cartilaginous hardness supply their place ; they 

 are rendered peculiarly soft and spongy by the 

 influence of mercury and scurvy upon the 

 system. 



The velum palati is a soft moveable curtain 

 stretching backwards and downwards into the 

 cavity of the pharynx from the posterior border 

 of the hard palate, but so continuous with it as 

 to exhibit no indication of their union. From 

 its oblique direction the buccal or inferior sur- 

 face is also anterior; it is concave, prolongs 



backwards the roof of the mouth, and presents 

 the median ridge already noticed on the under 

 surface of the hard palate. The nasal or supe- 

 rior surface looks upwards and backwards, is 

 smooth, convex, and continuous with the floor 

 of the nasal cavities; these surfaces terminate 

 in a thin border posteriorly, which is prolonged 

 downwards in the middle line to form the 

 uvula. The uvula is of a conical shape, and 

 varies in length and size in different indivi- 

 duals; it is occasionally found to be bifid at 

 its extremity; it gives rise on either side near 

 its base to two folds of mucous membrane, 

 called the pillars of the fauces, which descend 

 diverging towards the sides of the tongue at its 

 back part,leavingbetween them an interval which 

 is in a great measure occupied by the tonsil ; 

 the anterior pillar proceeds from the base of the 

 uvula in front, and arching outwards and down- 

 wards terminates at the side of the tongue a 

 little in advance of the V-shaped ridge of pa- 

 pilla ; the two anterior pillars together form 

 what is denominated the anterior arch of the 

 fauces. The posterior pillars constitute in fact 

 the free border of the velum ; they are nearer 

 to each other at their commencement than the 

 anterior, and from this circumstance (although 

 on a plane posterior) can be seen at the same 

 time with the anterior pillars on looking into 

 the mouth ; they spring from the sides of the 

 uvula to take an arched course outwards and 

 downwards and terminate in the sides of the 

 pharynx. The posterior pillars laterally, with 

 the velum and uvula above and the base of the 

 tongue below, bound the constricted aperture 

 between the cavities of the mouth and pharynx, 

 which is called the isthmus faucium ; the uvula 

 dropping in the centre gives the superior out- 

 line of this opening a double arched form : it is 

 extremely dilatable, and may be contracted 

 nearly to complete closure by the muscular 

 action of its walls ; it is essentially concerned 

 in the act of deglutition. The fossa which is 

 left on either side between the anterior and pos- 

 terior pillars is of a triangular shape, narrow 

 above where the pillars approach each other, 

 broader and deeper below as they diverge. 

 The lower part of this will nearly correspond 

 to the angle of the jaw. 



Muscles of the velum palati. These are on 

 each side, the circumflexus or tensor palati and 

 levator palati mollis, which descend from above 

 to be attached to the velum near its upper sur- 

 face ; and the palato-glossus and palato-pha- 

 ryngeus muscles, which descend from it to the 

 tongue and palate ; lastly there is the central 

 azygos uvulae muscle. 



The circumflexus palati, tensor palati, or the 

 peristaphylinus externus (pterygo-staphylin. 

 Chauss.) is a flat, thin muscle, lying to the 

 inner side of the internal pterygoid, and with it 

 occupying the pterygoid fossa ; it arises by ten- 

 dinous and fleshy fibres from the scaphoid de- 

 pression situated at the upper part of the inner 

 pterygoid plate, and extending more outwardly, 

 from a part of the external surface of the carti- 

 laginous portion of the Eustachian tube. The 

 muscle descends, partly tendinous and partly 

 fleshy, resting against the outer surface of 



