Politzer's text-book of the diseases of the ear and adjacent organs... / by Adam Politzer ; translated by Oscar Dodd ; edited by Sir William Dalby.

  • Politzer, Adam, 1835-1920.
Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: Politzer's text-book of the diseases of the ear and adjacent organs... / by Adam Politzer ; translated by Oscar Dodd ; edited by Sir William Dalby. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

    28/760 (page 12)
    on a section through the outer pole of tlie meuibrana tynipani these diameters are 8-1 and 4-6 nmi. respectively. The lengths of the different walls from the external orifice of the ear to the insertion of the membrana tympani are unequal. V. Troltsch in his measure- ments assumes as the exterior boundary of the meatus a sagittal plane, passing through the posterior margin of the orifice, and according to him the length of the superior wall amounts to 21 mm., that of the inferior to 26 mm., that of the anterior to 27 mm., and that of the posterior wall to 22 mm. On an average tlie length of the whole meatus is 24 mm., of which more than one- third is taken up by tlie cartilaginous portion. The meatus in its course from the external orifice to the mem- FiG. 13.—Horizontal Section of the External Meatus. •ft, Concha ; b, Tragus ; <:, Place of attashment of the cartilaginous portion ; d, Mas- toid process ; e, Anterior wall of the meatus ; f. Sin. meat, audit, extern. ; </, Membrana tympani ; h, Tympanic cavity (left ear). brana tympani displays several curves, which deserve full considera- tion in regard to examinations of the membrana tympani, as well as in respect to operations in the meatus. Although the whole meatus appears spirally twisted about its axis (Fig. 14) it may on the whole be assumed that the cartilaginous portion in passing inwards turns backwards and upwards, the osseous portion forwards and down- wards. The longitudinal axes of the two portions of the meatus therefore form an open angle forwards and downwards, and as the meatus from the place of union of the two portions slopes both outwards ■and inwards, the inferior part of the external orifice and of the membrana tympani must lie lower than the other parts of the meatus. According to the observations of Laufel and Symington, in the new-born the lumen of the meatus is wanting in the inner segment, as the membrana