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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    veniently divided, for our present purpose, into two parts:— 1. The conducting apparatus.—Consisting of the external ear (auricle and meatus) and the middle ear (tympanum, Eustachian tube and mastoid process). 2. The perceptive apparatus.—This, the essential por- tion, is made up of the internal ear or labyrinth (con- taining the nerve endings) ; the auditory nerve or portio mollis of the 7th cranial nerve (now usually described as the 8th) ; and the auditory centre, which is that part of the brain from which the nerve takes its origin. The perceptive apparatus, although the more im- portant part of the whole, would be of but little use without the conducting portion. The nerve endings being bathed in fluid, sound waves passing from the gaseous medium (the atmosphere) to the fluid one (the epilymph), would be almost entirely reflected and lost unless there were some means whereby they might be picked up and transmitted. This duty is performed by the membrana tympani and the chain of ossicles, the essential parts of the conducting apparatus. Equilibration.—The posterior portion of the internal ear or labyrinth, which comprises the semicircular canals and utricle is, in all probability, devoted to the second and minor function of the organ, equilibration, or the sense of motion and equilibrium.* The nerve fibres of this posterior portion form part of the portio mollis and pass through the cerebellum. Disturbance of any of these parts gives rise to those peculiar pheno- mena known as auditory vertigo or Meniere's symptoms. * Some recent researches made by Steiner and Ewald seem to throw a doubt upon the function of the semicircular canals, but their observations have yet to be confirmed.