948 



PHARYNX. 



they become flaccid, and are loosely applied to 

 the posterior surface of the larynx, and so con- 

 tinued into the oesophagus : if examined from 

 behind, the pharynx is seen to be of great 

 breadth at the base of the skull, but narrows 

 until opposed to the buccal cavity, where it 

 again widens to contract somewhat abruptly at 

 its termination : its lateral relations to the ca- 

 rotid vessels and nerves of the neck have been 

 considered in the descriptions of the constrictor 

 muscles. 



3 . The cavity and its openings. The interior 

 of the pharynx exhibits a cavity of considerable 

 size, which is continuous with those of the 

 nasal fossae and mouth anteriorly and the canal 

 of the o?sophagus below. To study the varying 

 dimensions of this cavity and the different 

 openings which communicate with it, the pha- 

 rynx must be slit up posteriorly and in the 

 median line ; its greatest breadth is behind the 

 mouth, the buccal portion, which may be mea- 

 sured by the interval between the posterior ex- 

 tremities of the alveolar border of the lower 

 jaw, and is rather more than two inches ; thence 

 narrowing upwards, the internal pterygoid plates 

 will by their distance from each other, which 

 is about one inch, give the diameter of the 

 cavity at its nasal portion, while the distance 

 between the posterior edges of the alse of the 

 thyroid cartilage will denote its breadth at the 

 inferior or laryngeal portion : the antero-poste- 

 rior diameter can vary but little, in consequence 

 of the relation which the vertebral column has 

 to the pharynx behind : during the act of deglu- 

 tition these measurements are of course altered, 

 but there is much less change of form in the 

 upper or nasal portion of the cavity than in the 

 rest of its extent. Dropping into the cavity 

 from before backwards and from above down- 

 wards is the velum palati with the uvula de- 

 pending from the centre of its posterior border : 

 above this moveabie curtain are seen the poste- 

 rior openings of the nose with its median sep- 

 tum, the vomer : these are situated between 

 the internal pterygoid plates, extend upwards 

 to the base of the skull, and are limited below 

 by the velum ; they are quadrilateral in their 

 outline and continued into the upper part of 

 the pharyngeal cavity ; a little way within the 

 nasal fossae and along their outer walls are seen 

 the meatuses of the nose and the posterior 

 edges of the inferior turbinated bones; pro- 

 longing these latter backwards by an imaginary 

 line, we are brought to the openings of the 

 Eustachian tubes; they are two narrow ellipti- 

 cal fissures, their long diameters, about three- 

 eighths of an inch, directed from above down- 

 wards, and situated one on either side of the 

 pharynx above the soft palate, and impinging 

 the posterior edges of the internal pterygoid 

 plates ; they look forwards and inwards towards 

 the inferior and middle meatuses of the nose, 

 and are marked by prominent and rounded 

 margins internally; an accurate knowledge of 

 their relation to the nasal fossee is of practical 

 use in directing a probe or syringe into their 

 canals; behind the openings of the Eustachian 

 tubes are the longitudinal sulci which lead up- 

 wards and backwards to a cul-de-sac that occu- 



pies the angle formed by the sudden bending 

 forward of the aponeurosis of the pharynx ; 

 below the velum is the posterior constricted 

 aperture of the mouth, which will be again 

 referred to in the description of the soft palate ; 

 it is limited above by the velum, below by the 

 base of the tongue, and laterally by the poste- 

 rior pillars of the fauces ; the uvula depending 

 from the velum centrally gives it a double 

 arched outline above, but it is capable of as- 

 suming changes of form by the varied move- 

 ments of its boundaries, which are especially 

 concerned in deglutition ; below the isthmus 

 faucium and behind the base of the tongue is 

 the superior aperture of the larynx, surmounted 

 in front by the epiglottis ; it is a triangular 

 opening, the base directed forwards, and it has 

 also an oblique ditection from above down- 

 wards and from before backwards ; it is gene- 

 rally completely closed during deglutition by 

 the epiglottis being forced down upon it ; on 

 either side of the posterior surface of the larynx, 

 between the thyroid and cricoid cartilages, are 

 two gutters which lead downwards to the 

 cesophageal opening of the pharynx; this open- 

 ing has its long diameter from side to side in 

 the flaccid state of its walls, but assumes a 

 circular form when distended by the passage of 

 food through it. 



4. AIucous membrane and glands. The inte- 

 rior of the pharynx is lined by a mucous mem- 

 brane continuous with that investing the several 

 cavities which open into it; it is of a reddish 

 colour, and adherent to the muscular parietes 

 by a thin submucous areolar tissue ; from co- 

 vering the back part and sides of the interior of 

 the pharynx, it is to be traced along the under 

 surface of the basilar process united to the 

 periosteum through the medium of its sub- 

 mucous tunic, which at this part acquires con- 

 siderable thickness, and is occasionally the seat 

 of polypus; laterally and above it is reflected 

 over the guttural orifice of the Eustachian tube, 

 enters the canal, and is conducted by it to the 

 cavity of the tympanum, forming an exceed- 

 ingly thin lining to both ; continuous with the 

 mucous membrane, investing the upper surface 

 of the velum, it passes through the posterior 

 nasal openings into the nose ; it may be next 

 traced through the isthmus faucium, covering 

 the under surface of the velum and posterior 

 pillars of the fauces, to be continuous with the 

 membrane of the buccal cavity, while more in- 

 teriorly, after assisting to form the aryteno- 

 epiglpttidean folds of the laryngeal mucous 

 membrane, it is reflected over the posterior 

 surface of the larynx, to which it is connected 

 so loosely by an areolar tissue as to be thrown 

 into longitudinal folds, a provision for the dila- 

 tation of this part of the pharynx during the pas- 

 sage of the food ; lastly, it is continued into the 

 oesophagus. The mucous membrane above the 

 velum palati, upon its upper surface and within 

 the Eustachian tubes, is coated with epithelial 

 prisms, corresponding in this respect with that 

 which lines the greater part of the nasal cavities, 

 while below the velum the epithelium assumes 

 the lamelliform or scaly character. (See Mu- 

 cous MEMBKANE.) As it invests the upper 



