Essentials of the diseases of the ear arranged in the form of questions and answers : prepared especially for students of medicine and post-graduate students / by E. B. Gleason.

  • Gleason, E. Badwin.
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: Essentials of the diseases of the ear arranged in the form of questions and answers : prepared especially for students of medicine and post-graduate students / by E. B. Gleason. Source: Wellcome Collection.

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

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    Fig. 105. osity containing but one cell, the mastoid antrum. At the age of eight years the child's mastoid generally contains numerous other pneumatic spaces radiating from the antrum, and its topographical relations are well shown in Figure 101. At puberty the mastoid has become a distinct prominence, conical in shape, with its apex down- ward. It may or may not contain pneumatic cells in addition to the antrum; in fact, there are four distinct types of mastoid structure: 1. The pneumatic, in which the whole mastoid process is composed of pneumatic spaces communicating with each other and with the antrum, and lined with a continu- ation of the mucous membrane of the mid- dle ear. The pneumatic spaces may be large (Fig. 103) or small (Fig. 104). If the pneumatic spaces are small, one compara- tively large cell is generally found at the mastoid tip. 2. The diploetic, the entire bone contain- ing no air-spaces, but composed of diploetic tissue. 3. The pneumo-diploetic, in which pneu- matic spaces and diploetic tissue are both found (Fig. 103). 4. The sclerosed, in which the entire bone is composed of compact bone often as hard as a tooth (Fig. 105). What is the pathological importance of these types of mastoid formation ? Pathologically and surgically, the struct- ure of the mastoid process is of the utmost importance. In the pneumatic type of mastoid with large cells, pus from the antrum readily finds its way to the lateral surface, but in the diploetic, and more especially in the sclerosed type, there is greater danger of pus burrowing its way into the cra- nial cavity. The difficulties of the mastoid operation are also greatly increased by the compactness and hardness of the bone. Where a large cell is present at the mastoid tip with a thin median wall, pus Vertical Sagittal Section through a Sclerosed Mastoid Process, the cellular structure of which, with the excep- tion of an exceedingly small antrum, has been entirely replaced by dense eburnated bone (from a specimen in the author's cabinet).