Hearing and how to keep it / [Charles Henry Burnett].

  • Charles Henry Burnett
Date:
[between 1870 and 1879?]
Catalogue details

Licence: Public Domain Mark

Credit: Hearing and how to keep it / [Charles Henry Burnett]. Source: Wellcome Collection.

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    cavity with the mastoid cells. (Fig. VI., 8, also Fig. VII., 13.) It is thus shown how the drum-cavity communicates, in front, with the Eustachian tube and throat, and behind with the mastoid cells, and it can also be seen that air conveyed by the Eustachian tube to the drum- cavity is also conveyed to the mastoid cells. Wider and more intricate in their topography are the outer and inner tympanic walls. The outer wall of the drum-cavity is composed mainly of the drum-head. The bony ring in which the drum-head is stretched, forms the limit of the outer wall. In close connection with this wall, i. e. the drum-head, is the handle of the hammer and the chorda tympani nerve. (Fig. III., 9 and 5-11.) There are also on the upper and inner part of this outer wall certain folds of the mucous membrane, around the chorda tympani nerve, called the pouches of the drum-head. That fold in front of the hammer, be- tween it and the circumference of the drum-head, is called the anterior pouch, (Fig. II., 9;) the fold be- hind the hammer is the posterior fold or pouch, and is the larger of the two. (Fig. II., 3.) The inner demands close examination in order to understand its divisions. On this wall is a convex- ity, called the promontory, which is caused by the outward projection of the lower turn of the cochlea, yet to be described. (Fig. VIII., 5.) This eminence
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