Whatever the cause of these differences, there are wide variations in the number, extent and size of the cells in the temporal bone. As a general rule, the larger the cells the greater is the facility with which infection spreads through them. In the highly pneumatized mastoid processes it is not an unusual operative observation to uncover purulent disease in cells remote from the antrum. It is not clear why infections in the mastoid vary in their predilection for certain pathways. Neumann,1 however, called attention to this fact.
It is particularly true of the extensively pneumatized, large cell mastoids that the pneumatic structure extends about the bony labyrinthine capsule into the depths of the petrous pyramid. Just as the cells in the mastoid vary in number, extent and size, so do the cells of the petrosa; furthermore, just as in the mastoid an infection at times exercises