

THE PHAEYNX. 1143 



The posterior wall is nearly vertical, and may be considered to extend upwards as far 

 as to the level of the body of the sphenoid bone, where it becomes continuous with the 

 rounded vault forming the roof. 



The roof lies under the body of the sphenoid, and on each side it extends downwards 

 to the superior margin of the orifice of the auditory tube. It slopes from in front down- 

 wards and backwards to meet the posterior wall at the junction of the basil ar part of the 

 occipital and sphenoid bones, immediately anterior to the pharyngeal bursa a small 

 median recess in the pharyngeal wall, found constantly in the child arid occasionally in 

 the adult. 



The side walls, right and left, are occupied by the pharyngeal opening of the auditory 

 tube, and posterior to them, by a vertical slit-like depression leading into a recess, called 

 the recessus pharyngeus (Rosenmulleri). 



The^oor is formed by the upper surface of the soft palate. 



Between the floor and the posterior wall is the aperture, the isthmus pharyngonasalis, 

 through which the pars nasalis communicates with the cavity of the pharynx proper. 



When the soft palate is raised, this communication becomes closed, by contact of the 

 soft palate with the posterior wall, and the floor of the pars nasalis is complete. 



A number of important structures are found in the walls of the pars nasalis. 



In the posterior part of the roof, and superior part of the posterior wall, there is 

 a considerable accumulation of lymph tissue, known as the pharyngeal tonsil. It 

 is most distinct in the child, and becomes indistinct, or entirely disappears, in 

 adult life. It extends from the body of the sphenoid down as far as to the margin 

 of the occipital bone, and, laterally, as far as to the superior part of the side wall. 

 The mucous membrane which covers it is thickened and thrown into transverse 

 folds. 



In connexion with the inferior part of the pharyngeal tonsil, there is found, constantly 

 in the child and occasionally in the adult, a small median recess which runs upwards and 

 backwards in the wall of the pharynx for some distance, and is known as the bursa 

 pharyngea (Fig. 903). The origin and morphological significance of this pouch are not 

 yet solved. 



Enlargement of the lymph tissue here occurs frequently in children, and the swollen lymph 

 nodules are known as adenoids. The enlargement may become so great as to fill up a great part 

 of the cavity of the nasal part of the pharynx. 



Ostium Pharyngeum Tubae Auditivse. On each side wall is placed the 

 pharyngeal orifice of the auditory tube (O.T. Eustachian tube), an opening of a 

 somewhat triangular form, with a characteristic infundibular or funnel-like 

 appearance (Fig. 903). It is bounded superiorly and posteriorly by a prominent 

 rounded ridge, the torus tubarius (O.T. Eustachian cushion). This ridge is due to the 

 projection of the cartilage which surrounds the auditory tube superiorly and 

 posteriorly, but is absent inferiorly and anteriorly. The prominence of the posterior 

 margin (labium posterius) as contrasted with the anterior margin (labium 

 anterius) of the orifice, and the direction of the tube itself, which runs posteriorly 

 and laterally (from the pharynx to the tympanum), greatly facilitate the intro- 

 duction of a Eustachian catheter. 



The exact position of the orifice is of importance. It is situated . on the side 

 wall of the pars nasalis, a short distance (about ^ to inch) behind the posterior 

 end of the inferior concha,' and immediately above the level of the hard palate 

 (Figs. 902 and 903). 



I A slight ridge of the mucous membrane descends from the inferior end of the torus 

 tubarius on the side wall of the pharynx, and gradually becomes lost. This is known as 

 the plica salpingopharyngea. Another less-developed ridge, the plica salpingopalatina, 

 passes from the anterior border of the ostium pharyngeum downwards and forwards to join 

 the palate. In front of the latter lies the indistinct groove, the naso-pharyngeal groove, 

 which indicates the separation of the nasal cavity from the nasal part of the pharynx. 



The levator veli palatini in descending runs parallel to the tuba auditiva, and along 

 its lower border. As it enters the palate, it produces, particularly when in a state of 



i contraction, an elevation just below the pharyngeal orifice of the tube, known as the torus 

 levatorius (Figs. 902 and 903), which in its upper portion abuts against the lower part 

 of the orifice, and forms its base when that opening assumes its usual triangular shape. 



