Fang Y, Olewnik L, Iwanaga J, Loukas M, Dumont AS, Tubbs RS
INTRODUCTION: Approaches to the jugular foramen can be challenging. Adding to this difficulty is the potential for a bony septation to occur in the foramen thus subdividing its contents. Although such bony septations in the jugular foramen are known, the anatomic details of these structures have not been studied well. Therefore, the present anatomic study was performed. -METHODS: One hundred adult human skulls (200 sides) -nderwent evaluation for the presence or absence of a bony septation within the jugular foramen. The source, morphology, and size were all documented. A classification scheme was developed to better describe the varied types of morphology of the jugular foramen bony septa. Select bony septations were submitted to histologic analysis using hematoxylin and eosin and Masson's trichrome. -RESULTS: Bony bridges were found on 8.5% of sides. These were bilateral in 3% of skulls. Eight (47%) were incomplete (type I). Nine sides (53%) were found to have completely articulated bony bridges (type II) and these had articulation between the bony processes as either touching (type IIa), joint-like (type IIb), or completely fused (type IIc) morphologies. Multiple septa were observed on 2.5% of sides and these were classified as type III septa. Histologically, both incomplete and complete septa were found to be composed of normal bone tissue. -CONCLUSIONS: Our study found significant variations regarding the bony septa of the jugular foramen. Knowledge of this anatomy can be useful for preoperative planning and intraoperative navigation with approaches to the skull base that target pathology of the jugular foramen.