376 HEAD AND NECK 



On the lateral wall of the naso-pharynx, on each side, is 

 seen the orifice of the auditory tube, and posterior to it the 

 pharyngeal recess. The ostium fiharyngeum of the auditory 

 tube lies immediately posterior to the lower part of the 

 corresponding choana, at a level which corresponds closely 

 with the posterior end of the inferior concha. It is bounded 

 above and posteriorly by a prominent and rounded margin 

 termed the torus tubarius, which is altogether deficient below 

 and anteriorly. A fold of mucous membrane, termed the 

 salpingo-pharyngeal fold^ descends upon the lateral wall of the 

 pharynx from the posterior lip of the orifice of the auditory 

 tube. As this is traced downwards it gradually disappears. 



The dissector should pass a Eustachian catheter through the nose into 

 the auditory tube. Hold the catheter with the point downwards. Pass it 

 posteriorly through the right nasal cavity, along the septum of the nose, to 

 the posterior wall of the pharynx. Pull it towards the palate till the bent end 

 of the catheter catches against the back of the hard palate. Turn the point 

 through a quarter of a circle to the right side of the head and it will enter 

 the right auditory tube. If it is desired to catheterise the left auditory tube 

 pass the catheter through the left nasal cavity, and in the final stage turn the 

 point to the left side. 



In the natural condition of parts there is a deep recess 

 on the lateral wall of the naso-pharynx immediately posterior 

 to the prominent posterior lip of the orifice of the auditory 

 tube. This is termed the lateral recess of the pharynx. 



The roof and posterior wall of the naso-pharynx are not 

 marked off from each other. They form together a continuous 

 curved surface. The upper portion of this surface looks 

 downwards and may be regarded as the roof; the lower portion, 

 which looks anteriorly, constitutes the posterior wall. The roof 

 is formed by the basilar part of the occipital bone, and 

 also by a small part of the under surface of the basi-sphenoid, 

 covered with a dense periosteum and a thick coating of mucous 

 membrane. The posterior wall is supported posteriorly by 

 the anterior arch of the atlas and the anterior surface of the 

 epistropheus. In that part of the roof which lies between the 

 two lateral recesses of the naso-pharynx there is a marked 

 collection of lymphoid tissue, the pharyngeal tonsil. Over its 

 surface the mucous membrane is thickened and wrinkled, and 

 in its lower part a small median pit, termed the pharyngeal 

 bursa, may usually be found ; it is just large enough to admit 

 the point of a fine probe. 



The floor of the naso-pharynx is formed by the curved, 



