Jugular bulb position and shape are unrelated to temporal bone pneumatization.

The position and shape of the jugular bulb are undependable, and thus can add difficulty to temporal bone surgery. The present study addresses the hypothesis that position and shape of the jugular bulb correlate with the extent of temporal bone pneumatization. Systematic study was done in 25 unilateral cadaver specimens. Pneumatization was determined using both the classic Runström II radiograph, and computed tomography. Jugular bulb shape and position were determined by anatomic dissection and computed tomography. No association of jugular bulb shape or position, with pneumatization, was found. However, the dissection-determined distance from the plane of the lateral semicircular canal to the roof of the jugular bulb (2 to 15 mm), had a good correlation (r = 0.70, p less than .001) with the distance from the internal auditory canal to the apex of the jugular bulb (1.5 to 15.0 mm).