On the structure and function of the rods of the cochlea in man and other mammals / by Urban Pritchard, M.D.

  • Pritchard, Urban.
Date:
[1873]
Catalogue details

Licence: Public Domain Mark

Credit: On the structure and function of the rods of the cochlea in man and other mammals / by Urban Pritchard, M.D. Source: Wellcome Collection.

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

    2/8 page 151
    The other, the lamina spiraHs membranacea, proceeds directly outwards from the limbus to the ligament of the cochlea. This membranous lamina is composed of two horizontal mem- branes, having between them certain delicate structures. The upper of these (the membrane tectoria) arises from the limbus just external to the membrane of Reissner, and passes du'ectly outwards, covering and overlapping the end of the limbus, but not actually reaching the ligament of the cochlea (Fig. II.). It may be well to state, by the way, that on this point I differ from most of the previous writers, with the exception of Bottcher. The portion which covers the limbus is moderately thin, but the outer portion which overlaps it is exceedingly thick, and the whole is marked with radiating wavy lines. The lower, or membrana basilaris, arises fi'om the lower lip of the Hmbus, while its other end is firmly attached to a well-marked ridge on the ligament of the cochlea. Between the membrana tectoria above, and the membrana basilaris below, are situated the so-called rods of Corti. Tlie Rods of the Cochlea. These interesting little bodies were first discovered and de- scribed by the Marquis of Corti, whose name they now bear, and although since then many observers have studied and written on the subject, yet scarcely two are agreed as to their exact form, while many of the later authors have gone so far as to state that their shape is of a most varied character. The greatest difference of opinion exists as to the shape of the rods at their articulation. Deiters described them very minutely in his first paper, but in a second communication he completely altered his description of them. The following is a free translation of an extract from Deiters' first paper in Siebold and KoUiker's ' Zeitzchrift von Wissenschaffc Zoologie,' vol. 10. The outer rods do not directly join the inner, but are con- nected by a curious body, which partly belongs to the true rods of Corti and partly to the lamina reticularis, and which we will call the middle union joint. These middle joints vary much in form, owing to their easy compressibility, and have not on that account been as yet properly distinguished. This (middle joint) will best be likened to a boat which terminates at one end in a pointed keel, and at the other in a straight back or plate. In the natural position this back plate is turned upwards and lies parallel to the membrana basilaris; the keel, on the contrary, looks downwards and somewhat forwards The back plate is nearly rectangular in form, but only the anterior corners are perfect, the posterior being rounded, and perhap only appear angular on account of the plates lying side by side.'
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