PRACTICAL CONSIDERATIONS : THE MIDDLE EAR. 1507 



The Eustachian Tube. — The superior orifice of the Eustachian tube is in 

 ihe upper part of the anterior wall of the tympanum, and is therefore, not well 

 adapted for drainage of that cavity. The tube is directed downward, forward, and 

 inward to the side of the naso-pharynx, where it is on a level with the posterior end 

 of the inferior turbinate bone. -In children it is wider, shorter, and more horizontal, 

 so that in infection of the middle ear drainage in them is better, but, for the same 

 anatomical reasons, otitis media is more likely to follow pharyngeal and tonsillar 

 infections. The pharyngeal orifice is bounded above and at the inner side by the 

 prominent cartilaginous arch which encloses a funnel-shaped opening. The mucous 

 membrane over this projection is thickened by a cushion of adenoid tissue, hyper- 

 trophy of which is frequently associated with pharyngeal adenoids and enlarged 

 tonsils, and may occlude the tube, ultimately causing deafness. The upper border 

 of the pharyngeal opening of the tube is a half inch above the soft palate, and the 

 same distance below the basilar process, below the hinder end of the inferior turbi- 

 nate bone and in front of the posterior pharyngeal wall (Tillaux). Immediately 

 behind this orifice is the well-marked depression called Rosenmiiller's fossa, the 

 depth of which is increased in cases of enlargement of the pharyngeal tonsil and 

 which may then lead to difficulty in the passage of a catheter into the Eustachian 

 tube. It may also, when recognized, serve as a useful guide to the orifice of the 

 tube. Injury to the orifice of the tube during operations in the naso-pharynx, 

 or at the posterior ends of the turbinates, may lead to cicatricial contraction and 

 occlusion, thus causing defective hearing. Ulcerations in the naso-pharynx may 

 produce a like effect. The length of the tube is about 37 mm. ( i ^ in. ) and its 

 pharyngeal opening is about 25 mm. (i in.) lower than the tympanic. Its upper 

 third (12 mm.) is bony, and its lower two- thirds (25 mm,) cartilaginous. The 

 narrowest part, the isthmus, is at the junction of these two portions. The lumen 

 of the cartilaginous portion forms a somewhat S-shaped slit, the Walls being in 

 actual contact, except during the act of swallowing, when the slit opens so that 

 air may reach the tympanum and equalize the atmospheric pressure" on the two 

 sides of the tympanic membrane. In the bony portion, though the lumen is 

 smaller, it is open. In cases of obstruction of the tube at its pharyngeal end — 

 as by pressure from a growth, or from a thickened mucosa — the outside pres- 

 sure predominates, the tympanic membrane is pushed inward, and buzzing or 

 "singing in the ears" results. Whenever the palate is raised or deglutition 

 takes place, the tensor palati and levator palati contract, and in so doing 

 open the Eustachian tube by traction on the fibrous tissue which unites the outer 

 borders of the fibro-cartilaginous scroll of which the tube is composed. Concussion 

 of the tympanic membrane from loud reports, as from the firing of great guns, 

 is minimized by breathing with the mouth open, thus elevating the soft palate, 

 opening the Eustachian tube, and equalizing the pressure on the two sides of the 

 membrane. 



Inflation of the tympanum is accomplished through the Eustachian tube, and is 

 employed for diagnostic, prognostic, and therapeutic purposes. Several methods 

 are in use. Valsalva's consists of a vigorous expiratory effort while the nose and 

 mouth are kept closed. Politzer inflates the tympanum through one nostril by a 

 vigorous compression of a rubber air-bag, while the patient is in the act of swallow- 

 ing. The opposite nostril and mouth are closed. The most satisfactory method in 

 difficult cases is by means of the Eustachian catheter. The instrument is passed tip 

 downward along the floor of the nose until it drops into the post-nasal space and 

 the posterior wall of the pharynx is reached. The tip is then turned gently outward 

 and withdrawn about i cm. when the slight resistance of the cartilaginous rim is 

 felt. After gliding forward over this prominence, it will engage in the orifice of the 

 tube. The ring at the proximal end of the catheter — which is in the plane of the 

 the curve of the beak and thus shows the position of the latter — is then directed 

 toward the external meatus of the same side (Bonnafont). The catheter may be 

 withdrawn, and the tip at the same time be turned to the opposite side from the 

 one to be catheterized, so that the beak of the instrument catches on the edge of 

 the vomer. It is then turned upward through 180°, and thus enters the tubal 

 opening (Frank, Lowenberg). 



