A manual of human microscopic anatomy / by A. Kölliker.

  • Kölliker, Albert, 1817-1905.
Date:
1860
Catalogue details

Licence: Public Domain Mark

Credit: A manual of human microscopic anatomy / by A. Kölliker. Source: Wellcome Collection.

    620/684 (page 600)
    AUDITORY NERVE. [sECT. 234. Of the zona membranacea, in the entire extent of the cochlea. This vessel, which is probably venous, always lies beneath the habennla denticulata, sometimes more internally, sometimes more externally • in the last half turn of the cochlea it is a capillary vessel, o'ooV'' m diameter; towards the base, however, it gradually reaches 0-013 m breadth, and is distinctly composed of two coats. In rare cases, there are two capillary vasa spiralia in the situation mentioned, and Corti has twice found in man, and in the sheep an outer vas spirale also, near the ligamentum spirale on the zona pectmata, but this did not communicate with the inner vessels, the zona pectmata m general being non-vascular. We have still at the close to notice the auditory nerve The nerve-tubes of its trunk measure in man 0-002' to 0-005' are extremely readily destructible, and possess only a delicate neuri- lemma. Between the tubules, numerous ganglionic cells are found m the trunk itself, and in the vestibular and cochlear nerves- these cells are bipolar, apolar, or unipolar, pale or pigmented, and measure 0-02- to 0-07- in man and mammalia; those cells which have only one pole, or none at all, are, probably, as Stannius suggests, only mutilated bipolar ones, seeing that the auditory nerve especially in fishes, may possess bipolar cells only, or scarcely any others. Similar cells, but smaller, are also found as above mentioned, in the cochlea and on the nervous trunklets m the vestibule {Pappenheim, Corti). Czermak has observed the übres of the auditory nerve to divide in the ultimate distribution on the ampullae and sacculus of the sturgeon; Harless and myself have seen the same thing in the frog, and Leydig in the chima^ra. With regard to the development of the organ of hearing, it may only be mentioned here, that, according to Huschke's discoveries, confirmed by Reissner and Remak, the membranous parts of the labyrinth are formed from the external skin by a process of intro- version, so that they might be compared in their origin to the lens and the vitreous humour; in this process, the layer of cells correspondmg to the epidermis is chiefly concerned, though not exclusively, as Remak believes; and to the introverted membrane are superadded the auditory nerves from the brain, and the remain- ing structures, both hard and soft, from the middle germinal lamma, and thus the organ is completed. Nothing of importance IS known with regard to the histological development of the soft parts of the labyrinth. For the investigation the organ of hearing, which only in the labyrinth piesents very considerable difficulties, perfectly fresh preparations are indis-