Handbook of diseases of the ear : for the use of students and practitioners / by Urban Pritchard.

  • Pritchard, Urban.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: Handbook of diseases of the ear : for the use of students and practitioners / by Urban Pritchard. 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.

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    PHYSIOLOGY OF HEARING. culatum internum and medullary fibres of the cortex. There is thus a decussation of auditary fibres very simi- lar to that which takes place in the case of the optic nerves. As already mentioned (p. 2) the vestibular fibres from the semicircular canals pass through the cerebellum. Lower down the auditory nerve receives fibres from nuclei seated in the floor of the fourth ventricle between and in front of the restiform bodies. Functions. Having now briefly considered the anatomy of the auditory apparatus, it may be well to add a few words upon the role which the various parts play in the pro- duction of the sense of hearing. The collecting power of the human auricle is of slight value, but still, to a certain extent, the sound waves are directed by it into the meatus. The meatus conducts them to the tense membrana tympani, and this readily picks them up and transfers them to the chain of ossicles with which it is in intimate relationship. These mobile solid bodies, vibrating as a whole, carry on the sound waves to the fluid of the internal ear by means of the foot-plate of the stapes. The membrana tympani and the chain of ossicles are necessary on account of the fact that sound-waves, passing from a gaseous medium (in this case, the air) into a fluid one (here represented by the epilymph), are almost entirely reflected and lost. But the tense mem- brana tympani is able readily to pick up the sound- waves from the gaseous medium and so transmit them to the solid ossicles, and through these they are trans-