A text-book of the diseases of the ear for students and practitioners . eriorly where the obliquely rising 4^ DISEASES OF THE EAR anterior wall of the tympanum curves towards the inferior wallof the osseous tube (Figs. 43, i, and 44, ot). The tympanicorifice of the Eustachian tube lies above this place at the levelof the upper third of the tympanum ; it is irregularly definedand inconstant in size, the height of which measures 4*5 mm.,the breadth 33 mm. The lumen of the osseous canal—thediameter of which, according to Henle, is about 2 mm.—diminishes slightly at its place of union with the car
A text-book of the diseases of the ear for students and practitioners . eriorly where the obliquely rising 4^ DISEASES OF THE EAR anterior wall of the tympanum curves towards the inferior wallof the osseous tube (Figs. 43, i, and 44, ot). The tympanicorifice of the Eustachian tube lies above this place at the levelof the upper third of the tympanum ; it is irregularly definedand inconstant in size, the height of which measures 4*5 mm.,the breadth 33 mm. The lumen of the osseous canal—thediameter of which, according to Henle, is about 2 mm.—diminishes slightly at its place of union with the cartilaginousportion ; in transverse sections it shows an irregular triangularcontour, brought about by angular projections (L. Meyer*). 2. The Cartilaginous Portion of the Eustachian Tube(cartilago tubae auditivae). The cartilaginous, medial part of the tube is attached to therough, irregular, oblique margin of the anterior extremity of theosseous portion ; it reaches farther up laterally than medially,because the lateral wall of the osseous portion is shorter than. Fig. 44.—Sagittal Section through the Entire Middle Ear of anAdult, Inner Half. op, Ost. pharyng. tubae ; te, Canalis tubae audit. ; ot, Ost. tyrap. tubae ; tp, Muse,tens. tymp. ; p, Promontory with the nervus tympanicus ; u, Inferior wall of thetympanic cavity ; st, Stapes ; sp, Muse, stapedius : /, Facial nerve ; an, Antrummastoid. ; w, w, Mastoid cells. From a preparation in the authors collection.(Left ear.) the medial wall. The cartilaginous tube is not, however, cartila-ginous in its whole extent, but is partly made up of a membranewhich completes the groove-shaped cartilage into a canal. The cartilaginous plate, turned in at its superior margin, forms,near its insertion into the osseous part, a narrow groove, theanterior external wall of which is broader than the posterior * Cp. A. Politzer, Die a/natom. unci histolog. ZergHederung des mensch-lichen Gelibr organs, p. 43. CARTILAGINOUS PORTION OF THE EUSTA
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