ANATOMY
Mouret and Portmann1 discussed embryologically the temporal bone, and the middle ear and its pneumatic cells. The latter cells are described in detail and are classified in a systematic manner. They also described the infectious paths which are divided in a preformed anatomic and a transosseous path. The interosseous paths are: the external and petrosquamous fissure, the internal petrosquamous fissure, the canalis subacutus and the glaserian fissure. The transosseous paths depend on the structure of the bones which are classified into central cortical, cortical exotemporalis or peripheral. The latter is always thicker than the former. The following forms of mastoiditis are differentiated: retro-auricular, posterosuperior, postero-inferior, mastoiditis of Bezold, jugodigastric, paramastoiditis temporozygomatic superficialis and paramastoiditis-temporozygomatic profundus. In conclusion the authors differ with Wittmach's theory. They believe that the eburnation of the mastoid process is not a result of chronic inflammation, but believe that the nonpneumatization results in individual influences which