The mechanism of the ossicles of the ear and membrana tympani / by H. Helmholtz ; translated from the German, with the author's permission, by Albert H. Buck and Normand Smith.

  • Helmholtz, Hermann von, 1821-1894.
Date:
1873
Catalogue details

Licence: Public Domain Mark

Credit: The mechanism of the ossicles of the ear and membrana tympani / by H. Helmholtz ; translated from the German, with the author's permission, by Albert H. Buck and Normand Smith. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    16/70 (page 16)
    Anatomy of the Membrana Tympan i. Before passing on to the discussion of the mechanism of the apparatus of the middle ear, I must make one or two anatomi- cal remarks, not with the view of bringing forward any thing materially new, but simply to give prominence to a number of small points, which as a rule are merely noticed and then pass- ed over by the anatomist, but which gain importance in a more thorough investigation of their physiological bearings. The opening in which the membrana tympani is set is formed from the squamous portion of the temporal bone and from what was once the annulns tympanicns, both of which in adults are firmly connected by a bony union ; not so firmly, however, but that in chiseling out a preparation of the ear, a break is likely to occur at this very spot of union—a circumstance which I found very annoying in exposing to view the connections of the upper part of the membrana tympani. Even on the dried adult bone this line of separation is still pretty clearly marked by two prominent bony spurs, which rise up, before and behind, on the boundary between both parts ; these separate a lower part. which is nearly oval in form and contains a rim for the attachment of the membrana tympani, from an upper part, which is irregular in outline and more strongly con- cave. The former belongs to the os tympanicum, the latter to the os squamosum. Fig. 1 re- presents the upper and anterior wall of the bony portion of the external auditory canal. The line of section was drawn parallel to this wall, a b is the surface of section of the anterior wall, which separates the auditory canal from the joint of the jaw: ed is the line of section through the posterior wall; b d is the outer opening of the auditory canal; a slight furrow // i, which in the Fig. i.