Anatomical relationship between position of the sigmoid sinus and regional mastoid pneumatization.

In order to examine the relationship between the location of the sigmoid sinus (SS) and mastoid pneumatization, 25 adult temporal bones were dissected. Pneumatization was evaluated according to findings during dissections of three separate regions of the mastoid: i.e., the sinodural angle (SDA) area, inter-sinofacial area and mastoid apex. In addition, the SDA and distance between the SS and vertical portion of the facial nerve, were measured at the second genu (G) of the facial nerve, the junction (J) of the nerve and digastric ridge and the midpoint between G and J.A good correlation was observed between pneumatization of the cells surrounding the SDA and the distance between the SS and facial nerve at the mid-point of its vertical segment. However, pneumatization of the inter-sinofacial air cell tract could not be correlated with this distance. A significant decrease in the values of the SDA was found when the air cells surrounding the SDA were poorly pneumatized. This study indicated a correlation between the position of the SS and pneumatization of the mastoid in the area of the SDA.