A text-book of the diseases of the ear and adjacent organs . tympanal opening of the Eustachian tube is about 2-5 than the pharyngeal opening. The length of the whole canal can only be determined approximately,because the commencement of its osseous portion in the tympanic cavity isnot sharply defined ; it amounts generally to 34-36 mm., of which the carti-laginous portion forms two-thirds. The narrowest part, the Isthmus tubes,which is situated in the cartilaginous section in front of its point of union * Compare Bischoff, jun., Mikroshopische Analyse der Anastomosen der
A text-book of the diseases of the ear and adjacent organs . tympanal opening of the Eustachian tube is about 2-5 than the pharyngeal opening. The length of the whole canal can only be determined approximately,because the commencement of its osseous portion in the tympanic cavity isnot sharply defined ; it amounts generally to 34-36 mm., of which the carti-laginous portion forms two-thirds. The narrowest part, the Isthmus tubes,which is situated in the cartilaginous section in front of its point of union * Compare Bischoff, jun., Mikroshopische Analyse der Anastomosen der Kopf-nerven, Miinchen, 1865. 40 OSSEOUS PORTION OF THE EUSTACHIAN TUBE. With the osseous portion, measures in the corrosion preparations prepared byBezold 3 mm. in height, and not more than $ mm. in width. Its distancefrom the ostium pharyngeum averages 24-26 mm. a. The Osseous Portion of the Eustachian Tube. The osseous portion of the Eustachian tube, bounded above by the canal ofthe tensor tympani, and below and towards the middle by the carotid canal,. Fig. 42. It i a -Eustachian Tube and Tympanic Cavity. a, Membrana tympani ; b, Head of the malleus ; c, Lower end of the handle of themalleus ; d, Body of the incus ; e, Short process of the incus ; f, Tensor tympani ;g, Ostium pharyngeum tubae ; h, Isthmus tubae ; i, Ostium tympanicum tubae.(Right ear.) is a prolongation of the anterior portion of the tympanic cavity directedinwards. The boundary between the tube and the cavity, however, is not avery marked one, because the superior and lateral walls of the latter mergewithout interruption into the former. On the under-side the boundary isbetter defined, especially where the obliquely rising anterior wall of thetympanic cavity curves towards the inferior wall of the osseous tube ( and 43, ot). Above this place is situated the ostium tympanicum tubaEustachii, irregularly defined and inconstant in size; its height, accordingto Bezold, is 4*5 mm., its width 33 mm. The lu
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Keywords: ., bookcentury1800, bookdecade1890, booksubjecteardiseases, bookyear
